I haven't played Satisfactory since the water update, so I have no idea if my approach still works, but IMO the easiest way to design an efficient factory is to not bother trying to balance anything, and scale out in only one direction as needed. Feed everything along a central stack of belts, and multiplex inputs/outputs via splitters/combiners so any individual machine line will always have throughput.

It doesn't make for a very exciting build, but it's very rote and dependable.

Also - build the entire thing high up in the sky.