An idea (if it is possible):
Have a splitter that prefers to pass the goods through on the input belt's side. But only if/when that side's output is blocked, then start outputting to the opposite side belt.
Likely the single-belt lane balancing would continue, or not. I am talking about only actually splitting goods when the entity can no longer pass-through. ie: Left belt passes out to left belt only, until full. Once full, then starts dumping out excess to right belt, and returns to filling left belt when room.
Maybe this is somehow an optional toggle on each splitter, or an additional splitter type? (You decide if you choose to implement the idea)
I don't know how much control is available in the api for individual entity manipulation and configuration when placed in the world (or is it strictly limited to prototype definitions for various configurations)
