Philips is nice because (untrained) people naturally will over-tighten the fuck out of every screw they encounter. Philips cams out and prevents them from going too far overboard. In fact its literal design goal was to make a screw that is hard to over-tighten.
I know if we used torx on some of our products, we'd spent 10000% more time on removing snapped screw bodies.
Is there a decent convention for how much a screw should be tightened, or is it fully case-by-case?
For day to day, 95% of the time you can tighten a screw gently until it stops, its head fully against the surface, then just "snug it up" a bit to seat it.
"Snug it up" is of course vague, so refer back to line 1.
I only buy the torx/star variants, since they're just superior.