i play right handed...
and nowadays i practice with the guitar resting on my left leg.
its a more natural position when your left hand goes higher up the neck.
and your right shoulder doesnt feel as stressed.

few others do the same way, john petrucci being one of them.

whoever does it that way will need to elevate their left leg slightly.

this leads to another point.
in that position, to me, is about the similar position as when its strapped on standing up.
so unless, you're the kind who prefers strummy strummy power chord stuff...or some weirdo who practices for 2-3 hours standing up...

your guitar position when practicing sitting down, should be the same as strapped on.
especially important for those guys who like to blaze away, so you wont have to do any adjustments to your technique.

no.
80s were shredding.
90s were wank-less, d***-less.
then now its wank-fest time.