Those would be perfect splitter speeds. The current vanilla input speed is the same as one belt. Problem is, the splitter has TWO inputs. This means that you need one fast splitter for balancing standard belts(or worse, to balance vanilla fast lanes you would need FIVE fast splitters) which is not at all resource-efficient.
the splitters do not need to go faster to properly ballance, you can check yourself, 2 belts in and 2 belts out and it will still work fine, even at full speed
