If you have a bird's nest at the battery terminals do your best to get rid of it. Get some H.D. buss bars and make all the connections to the rest of the boat at the busses. Then use one heavy battery wire to each buss bar as required. If you have parallel batteries for a bank then make each positive wire from each battery the same length as each other. Do the same for the negative wire. It does make a difference.
I did that many years ago and am glad I did. I had the potential of the following problem.
I have been helping a friend undo a mess. He has a birds nest at the battery terminals and during the the last battery changeout one lead got misconnected and he had 24V on part of his system. Part of the problem is nothing was labelled or colour coded so when one lead got out of place guess what, it was connected to the wrong polarity. Ruined his alternator controller,, seems to have damaged the battery charger, the inverter didn;'t like and it lost some smoke. Of course he is electrically challenged, hired stuff out, so wasn't really aware but regardless it can happen and one of the reasons is the 20 odd connections all over the place.
With the buss bars, once done, when the battery needs replacement there is only a single pos and neg wire to be undone. No other leads need be touched.
Of course colour code andlabell also but at the least the busses.