That really depends. I have never read the whole jQuery documentation, even though I use it on a regular basis. On the other hand I have read the whole docs for VueJS (1), but never actually really used it. Whatever it takes to get the job done I guess.
I understand the sensation of reading docs and discovering new stuff, but I am only ever tempted to do that when I'm on the hunt for a good blog post (and I don't even have a blog).