In the video above i talk about priority lane balancers i made, and how useful they can be for your smelting and production needs by saving lanes of materials and better utilizing your productivity modules. They do the job a common balancer plus a lane balancer can do for production - smelting while being significantly smaller saving you both production and UPS.
To explain here, it utilizes the kickback of a belt that stalls from the production that is not entirely consumed to provide material to an extra belt while lane balancing that extra belt. The result is similar to having a balancer from less belts to more belts and a lane balancer in line while being significantly smaller and using way less splitters.
https://factorioprints.com/view/-NLkRxC0vlCGUjxO5EB1