[Jim E]

This confused me a little too. The best way to describe the blocks is to treat each block set, red or black with jumpers installed, as a single point. Each terminal can be used for either inputs or outputs. Therefore, you have 8 terminals per block set. If the wire is a smaller gauge like 14 to 18, it would be okay to double up 2 wires into one terminal. This is especially true on the grounds. Anything from 12 ga. and larger is probably too large to comfortably fit into the terminal opening.

Try to avoid daisy-chaining the black return wires. If a fuse panel is wired to a particular circuit, it's preferable to ground the circuit to the panel and then the panel to the block.
DO NOT daisy chain the ground returns from the maxi-panel (40A) to anything but the distribution block. You will experience wierd voltage drops and could possibly create a fire hazard from overheated wiring.