Depends. Im dyslexic so the book needs to be damn intresting or I cant get through it. If Im real intrested I dont even notice Im re-reading everything 5 times. If not, I get frustrated. But I can loose myself in a very good book, it just has to be good. So thats my fiction.
Non-fiction I do often. I research a lot. I read and teach myself everything possible. Such as just a few weeks ago I bought a lock picking set, learned how to pick a 5 pin lock in about 30 mins. Now I can pick it in a few secs. Everyone keeps asking me why, I just have to always be learning something new. Im always first to admit Im wrong but if so Im going to go find the right answer and usually backwards and fowards.
Next up, hopefully, is learning how to fix my car.
If I dont know a term I go read about it. If I hear about something that seems intresting I go research. If I need something fixed I usually research to see if I can learn to fix it. I also took apart things like our microwave growing up and found a set of encycolpedias when I was little in the garbage and took it home and they were my books growing up.
It creates issues though, my brain is continiously non-stop calculating and problem solving, it never turns off.
Which I would rather do is likely the non-fiction due to wanting to learn. Id rather do that than loose myself in something not real any day. And its a damn good distractor too.