I think I'd have difficulty listening to an instructor if they dished out absolutes.
Do what's comfortable - so long as it works. I'm only learning, but that's how I go with things. I don't focus on mechanics much, if at all.
I spent years trying to improve my golf through instruction and getting the mechanics 'right', only to come to the realisation that, for me, relaxation, rhythm and timing provide far more improvement. Trying to do it 'right' just ruined all three. I regularly play with blokes who have 'terrible' technique and swings that just shouldn't work, but they whip my butt on the scorecard.
Hendrix played his strat upside down and restrung. It's not an analogy to genius though.