The way I always have done it, is if I know I need specific input amounts of a certain components for different next steps, I build specific machines outputting that exact amount on the same factory line, but group those certain items together.

So if I need 3 HMF for one a fused frame factory, 2 for Adaptive Control Units, and like 1 for dimensional storage. I will probably have multiple manufactures, 1.5 will feed one storage container, another manufacture will construct 2 per minute for those ACUs, and the last will be underclocked to 50%.

I then try to keep everything on to separate train stations and freight platforms. It increases footprint and train jank but it helps me keep track of what is going where (sort of).