One bank as long as you put a fuse between those banks!!
You're increasing the available fault current dramatically so the fuses or breakers, you should already have, can be overtaxed during any fault.
You also are increasing the likelihood of an internal cell fault in-system since you're connecting more cells together. A cell can fail shorted in which case ALL the batteries in the entire bank will go into major discharge into that shorted cell leading to some spectacular heating likely followed quickly by an intense fire. To completely avoid this scenario you put properly rated fuses between each battery and the main bus. If any battery has a cell short event that battery will be cut out of the herd by the fuse limiting current in or out of it.
You add up all the amps available from all the battery sets but the one for the battery being protected.
You look at the battery data sheets. One might be 4kAmps one might be 2kAmps and the other might be 3kA. Total 9kA.
Find a fuse type that can interrupt at least 9kA as that would be what's being contributed to a shorted cell in the fourth battery.
Next figure out how many amps your loads (inverters) can be expected to draw. Lets say it's a 3kW inverter. 24V batteries.
3kW/24V = 125A
Continuing the same example. You have four banks. 125A/4 = 31A each would be needed in a happily matched and shared setup. But to handle contingencies maybe double that 60A. Run 60A breakers or fuses from each battery bank. Breakers let you disconnect batteries more easily than fuses.
Of course you'd have to have 60A safe wire from each of these to the main bus.
An appropriate fuse or breaker to the inverter capable of running the inverter at it's maximum draw endlessly protected by that main bus fuse.
