Right. The problems I have is that none of these articles or discussions have ever measured a difference in the real world, and they all assume, with no empirical basis, that these low resistances are really low and the only ones that matter.
Want to know what would convince me? Measuring a real world difference.
Use a real world installation with bilge pump take-offs, gauge take-offs, crimped connections, components that have been in a boat for a while.
Charge all the batteries in parallel with equal length wires. Measure state of charge. Discharge them with equal length wires. Measure state of charge twice, difference. Once after a settling time and very, very brief discharge to get a good initial measurement, and one after the high draw load had time to take capacity down to about half. Repeat a few times to establish normal variation.
Repeat the experiment doing the same thing charging and discharging with the "same sided" arrangement. Quantify the difference that has been made. Compare it to other measured variations.
Science isn't just about producing hypotheses and building models with them. It is about producing hypotheses, building models with them, using those models to make predictions, and then testing those predictions.
We /know/ that this makes a difference in a perfect world. But does it make a difference in the real world? No one, to my knowledge, has ever shown that it has. Not by measuring charge or discharge disparities, not by measuring temperature disparities, nit by measuring water leve disparities, not by measuring lifetime disparities.
If one is redoing one's system, of course it makes sense to do this. There is no harm and only good can come from it.
But if one has a setup that is working fine and there is no observed problem, adjusting this wouldn't be high up on my to-do list.
If one has a problem one wants to solve, e.g. not enough house capacity, and the only thing preventing a solution is a slight variation in wire length, I'd recommend solving the problem. After decades of folks wiring batteries the "wrong way" I don't think folks have observed a massively high rate of premature death. No doubt there could have been some impact that went unnoticed given that we observe batteries as a whole system and they impact each other. But plenty of people have bade their boats better fit their needs by adding batteries with different lengths of wire at most modest penalties in battery life.
And, again, some mitigation is possible, such as using higher gauge wires, etc.
This also probably matters a lot more to those stacking tons of pairs of smaller batteries vs those stacking a couple of 8D batteries.
From the peanut gallery...
A colleague had a motto on his letterhead "Every knot was once a straight piece of string"
