MOST 4 strokes are lubricated by combustion blow by. That means they aren't constantly getting the lower end washed with fresh fuel like the two strokes. The bearings tend to take on as much oil as they need and the rest goes out the breather. That is probably why less oil was used in some 4 stroke blends.

YS 4 strokes are different! The get a fresh cleaning every stroke so they need more oil.