I scan over them, but that's about it.
I generally am a "do then read" type person (maybe take out the read part if I can do it).

If I need a particular piece of information, Google is probably quicker than digging out a manual and finding the relevant information (if it's even there).

Usually I don't read them unless there's a character bio or story, but if there's something I don't understand or missing I'll usually read it.

I always read them.