One thing I have found over the years is that even without any sort of balancing packs will now stay reasonably well balanced for a long time, if the pack is only run over a moderate SoC range. This never used to be the case in the early years of using lithium chemistry cells. Last year I ran a fairly big pack between about 20% SoC and 85% SoC for around 30 or so cycles, with no balancing at all, I just monitored the cell group voltages carefully. TBH, I was surprised at how well the pack stayed in balance, especially as it was made up from a mish mash of cells left over from another project.