That may be a good way to start thinking about who you are creating for.
If they don’t read books that may be a concern they don’t read blogs or essays either. If they only read short books, it may not be best to hit them with a long one. If they like books with pictures, it may benefit you to put those in your work. If they like a mix of entertainment, perhaps do that as well.
Looking at other behaviors in our audience is a good way to get a feel for the format. Though it’s always a little dangerous to look too closely to what others are doing and try to repeat that. You are you, not others. If you work differently, that can still work, but someone who hasn’t read a 500 page book ever isn’t likely to start unless you REALLY sell them on it, which is a hard thing to do because marketing isn’t convincing.
Research and understanding is a huge part of any project, some can be done before starting, but usually most of it has to be learned along the way. Look for patterns and answers, but don’t let that search stop you from doing the actual work.