I know that all pos battery and all neg battery cable lengths should match running to a Lynx power IN bus. Why is the additional length of the bus bar not considered? I know it's a far smaller AWG (equivalent) compared to, say, 2/0 AWG with low resistance but I would think it would still figure in some calculation, no? The bus bar on the Lynx Power In is ~256mm2 which is really close to 500MCM wire.

Would it be good to wire the 4 x batteries diagonally into the Lynx Power In?

I assume that all positives and all negatives do not need to be the same length as long as all the positives are the same length and all the negatives are the same length?