I'm definitely using one big main busbar on my next expansion.
I'm happy with my current DIY mini cabinet busbar but after this winter, so far, I need a lot more battery.
I'm still trying to find a large cabinet, I've contemplated the idea of finding an old walk in freezer and using it as power room... Weld up some simple racking with angle and C channel to hold stacks of cells...
Tiny space heater would keep the cells happy and I could save a ton (or more) of coal running the basement colder. I'd also save on electricity taking some load off the mini split.... Yea, I really like that idea; hell I could even relocate it to the unattached garage.