I would ignore this advice and keep doing wut ur doing in terms of exercises. Although legs twice a week is strenuous, if ur seeing poundage gains then stick with it.
Only 1 set of anything is a pussay's way out, esp for squats and deads. Compound lifts at least 3 sets each.
I'm curious as to how much weight fapolantern puts up on these lifts to make a bold and irresponsible claim of 1 set for squats and deads each. Sure it taxes CNS but not to an extent to only do one set out of fear, smh