Perhaps in many cases. However, I was seeing diverging voltages across the bank which got worse with each cycle, it was quite disturbing. (about 5 cycles into the bank use)
Each string has midpoint monitoring and I was seeing the balance go outside of 2% top to bottom half of each string. 2% is about the point where the voltage difference can cook the hot cell.
Interestingly, with all of the work
that is going into Lithium banks, Victron has recently released Flooded Lead Acid active balencers. Unfortunately they are only available for 12V batteries for 24V and 48V banks. Neat device and it would be possible to use with 6V batteries but not be able to automatically balance between the 2 batteries making up a 12V half string in the bank.
Definitely thinking that if I put the batteries which tend to be higher voltage (out of the series set of 4) in the top half of the series and the lower voltage batteries into the bottom half of the series I would get the benefit. They are inexpensive devices which basically turn on during the high voltage part of the charge cycle and shunt a small amount of current
around either the top half or the bottom half of the string to reduce the charge rate slightly (about 0.7A max, appears to have some step resistor which adjusts the amperage to balance the charge voltage).
Even if it does not significantly change the battery life, it would significantly reduce the water consumption
of the cells with higher voltage across them in the string which would be nice.
At any rate, can't imagine that working to balance the bank is any worst than a waste of time, probably can't hurt the batteries