yeah, I do that, on London Calling BV's at the same time as sliding up to the 7th fret, can't do that without looking.
Once read Macca used to practice while reading the paper so he could play without thinking about it, I've done the same while watching TV (not reading the paper)
As regards learning words, I do open mic on acoustic guitar, I always learn the words (one of my pet hates is singers who use cheat sheets), I sing them to myself while walking the dog, once they're in there they usually stay