I wonder if by saying this:
In my opinion, the reality of worldbuilding is that, generally
speaking, worldbuilders shouldn't focus too closely on the details.
you are trying to impose your views and values on the entire community. You bring one decent example demonstrating that sometimes asking for details is unproductive. However, does it apply to everything?
Different audiences and different creators prefer different levels of detail. Perhaps, you are one of those readers who skip lengthy descriptions of minor details. However, there are plenty of Jordan fans who praise his works and the amount of attention (and words) he gave to clothing, hairstyles, scenery, etc.
Details are what makes fictional worlds real. And details are also what ruins fictional worlds. It is very easy to get the big picture right, but it is extremely hard to get all details right. Just recall all those zombie films where character never run out of bullets or gasoline no matter how much time has passed since Day 0. Or think about all those fictional societies that 'develop' cultural traits and patterns that are unsustainable and/or defying everything we know about humans.
Should not a stack dedicated to worldbuilding help worldbuilders get details right?
Some additional thoughts:
It is not your or my place to make decisions on behalf of the questioner when it comes to details they need. It is the prerogative of the creator of a world to choose what to include and what not to include in their world and how deep they want to delve into specifics.
People do not know what they do not know. One's understanding of a subject may not be deep enough to be capable of discerning which details are important and which are not. It is always better to leave these matters to the creators themselves.
I also want to mention that lack of details leads to really bad answers. For example your answer to the question about loss of knowledge after the apocalypse. You ultimately end in self-contradiction and refute your own thesis that it's very hard to lose knowledge. A brief summary of weak points in your answer is below.
I'm afraid most of the answers you've been given make some serious assumptions that are, frankly, false. It's very, very hard to lose substantial information — even after a nuclear apocalypse.
Human history is full of instances where most of the information associated with a specific human culture has been lost almost completely. The loss of information (for example, traditional crafts and building techniques: Kimono-making, traditional oven building in Russia, organ building in Europe to name a few) happens today as well. But perhaps you do not regard dying-out technologies as substantial enough. You could've provided details explaining what substantial information means, but you did not. And as such your statement is false.
I apologize that this seems trite: but generally speaking, people aren't stupid. Almost everyone who survived the apocalypse would be literate (can read and write) and would pass that along to their children. Why? Because knowledge is power.
First of all, literacy is not education. It is just an ability to write and read. Secondly, historically high levels of literacy were associated with the existence of robust educational systems and/or religions that require the ability to read scriptures (e.g. Islam). Thirdly, there are no historical examples of high levels of educational attainment in poor societies. Education and pursuit of knowledge require full bellies and spare time.
Not necessarily knowledge of, say, quantum physics... but knowledge of business, fundamental mathematics, mechanics, civil and structural engineering, electricity, etc.
So, how much knowledge is going to be lost? You also do not mention art, philosophy, history, technological know-how, languages, and many other areas. Are these not knowledge? Or do you imply that art, history, and philosophy are somehow hard to lose (your premise is that knowledge is very hard to lose)?
The world is a very structured place. Schools would quickly reform because, per #1, people generally aren't stupid. You'll have plenty of people who know that failing to train the next generation is a really bad idea.
You make a good point here. However, you miss one important details: Next generations will be trained only in things that are necessary and sustainable. Farmers won't train painters, writers, or philosophers. A lot of non-essential knowledge will be lost.
We're addicted to technology. Yes, humans can figure out how to "live off the land." But realistically, you'll have people getting generators, computers, and the lights working very quickly. Even small town hardware stores have generators ready to sell and you can make a passable biodiesel fuel out of cooking oil (and cooking oil comes from both vegetables and animal fats...).
How long the generators will last? This is a very important detail. Can your generators last long enough to repair/rebuild infrastructure? Also, are your generators enough to power data centres?
Even a nuclear apocalypse wouldn't destroy every library in every city (and university, college, school...). Books will be everywhere. In homes, in stores... everywhere. The world wouldn't lack for books unless your story drives a reason for those books to be destroyed.
Do books contain ALL knowledge? No. One of the most obvious examples is practical knowledge and skills. Take for example cooking. You can learn theory from books. Books can even give you precise recipes. However, if you want to learn cooking skills an expert's guidance and supervision would be the most effective. Of course, you can learn things on your own. However, how much time and resources would it take? Is it even feasible in a post-apocalyptic setting?
What kind of books a school library has? Well, it has various textbooks and some small collection of classics. It might have some odd books as well. However, this kind of library contains only a small fraction of knowledge. Moreover, it is often simplified (textbooks) and/or ideologically biased (because schools are not unbiased).
How many small towns and colleges have decent book collections? Very few. Books are expensive and troublesome to store.
You also mention stores. Stores do not stock books that are not popular with their customer base. Therefore, their stocks are representative of the interests of the local population rather than the accumulated human knowledge.
There is one more important detail in regard to books. Modern books are fragile and modern libraries rely on a controlled environment to preserve books. If post-apocalyptic conditions are unfavourable a lot of books will be partially or fully damaged by moisture, rot, mould, etc. Most of the frequently used books (like repair manuals) will not last long because they are not meant to withstand extensive wear.
99.99% of the technology we use today was invented in the last 150 years. This is incredibly important to understand.
You are missing an incredibly important detail: The technology and industrial expansion of the past 150 years were not built from scratch or on the ruins of the previous civilisation. They relied on industry, expertise, knowledge, supply chains, and resources that already existed and properly functioned.
If your apocalypse was so thorough that it destroyed 90% of the population (leaving some 770 million people, at least half of which are adults...), you'd still have so many people with so much knowledge in their heads that it would be believable to have everything back to today's standards in 150 years.
770 million is a big number, even an impressive one. However, without knowing details related to demographics, population density, the scale of destruction, specifics of post-apocalyptic social structures, and state of communications it is just a number that does not have much predictive power.
If all major population and industrial centres are destroyed (which is the most likely outcome of a properly planned nuclear apocalypse) the majority of specialists required to rebuild just technology to today's levels will be lost. A lot of specialised knowledge will also be lost.
Yes, you have the radiation problems... but you have people with modern medical knowledge and medical supplies literally everywhere. You wouldn't have the mortality problems of the middle ages.
This situation will last for the first couple of decades. What happens after old doctors die and supplies exhausted will depend on the success of reconstruction. If people do not manage to restore the pharmaceutical industry and train medical personnel high mortality will be back.
SciFi loves the idea of a Mad Max-style apocalypse, where whole groups of people have somehow regressed and access to knowledge is mysterious. In reality, the world is swimming in knowledge. Oh, we might lose a lot of the things that don't affect everyday life (like astrophysics and quantum physics) and the destruction may have made it difficult to bring the highest tech back quickly (like nanometer-geometry computer chips).
Here you finally give some details and you immediately state that 'a lot of things will be lost'. Isn't it self-contradiction?
But electricity, chemistry, mechanics... and books... would all be in use from 10 seconds after the bombs hit. And there's so much stuff available that resources would exist for years... even decades....
The real question is how long it will last. And the answer to that will depend on details.
Do not underestimate just how much knowledge is in the head of the average 35-year-old person (much less the 60-year-olds...). Your real challenge is justifying its non-existence. That will be a contrivance, not an inevitability.
It really does not matter how much knowledge a particular individual has if they cannot pass their knowledge onto others.
Oh, one more important detail: your answer focuses on the state of affairs immediately after the apocalyptic event, while the question asks for a timeline or future events. You talk about the future only once (suggesting that we can go back to current levels of technology in about 150 years) but you provide no valid support for your statement.