Only put on belts, that are not bent. This has been discussed in a different thread and i put this here, to not forget it.
Rest of this post, is just a copy, of the originally post, so i don't forget about it :)

Zanostra
- a month ago

I have been thinking,
you say it is not possible to detect if belts are bent,
but is it possible to detect if there is an adjacent belt pointing towards the main one maybe?

https://pasteboard.co/IZlAKiL.png

in this screenshot in all four examples there is only 1 belt leaving the balancer.
maybe that particular belt can make a check on it's left and right ( the circles adjacent to it ) to see if there is also a belt, pointing towards it.
but only one of the 2.
the most left example is 0 belts pointing, meaning the belt is not bent, so take items from the balancer.
the second left example is 1 belt pointing, meaning belt is bent, so do not take items from the balancer.
the second right example is the same, 1 belt pointing, so belt is bent, do not take items.
the most right example has 2 belts pointing, meaning the belt is not bent, so do take items from the balancer.

if this will be ups unfriendly, I actually think it won't be that big of a problem because it will probably only be in rare situations.