The final multiblock that contains crafting storage, optional crafting monitor, and crafting co-processors, must be an oblong. No L-shapes or T-shapes.
Here's my set up before I replaced the 4x4k storage with 1x64k and 3xco-processors and added a tenth column:
I think the reason my system gets backlogged is that I have interfaces keeping pure crystals and processors and glass stocked, so when I use a processor it sets a chain of re-stocking going that uses up most of the crafting multiblocks. If I was just crafting the components on demand, the 8 co-processors would handle all the steps. With the components being kept in stock in an interface slot, anything that uses items out of 5 slots causes 5 of the 9 multiblocks to kick in, wasting the co-processors. So I should break these up and have more of them with fewer co-processors, but that would eat a ton of channels.