I can tell by looking at my displays.
I'll be honest with you I see that 80%-20% or 90%- 10% mentioned on different forums and even on this one. I even ask awhile ago on this forum to someone that said that, what would the voltage be at those points and they didn't know.
With drop in batteries and depending on the bms for balancing cells that will be the deciding factor.
I know with my prismatic cell batteries and the bms 14.1 is good enough to balance my cells and reset the SoC capacity. No reason to go high or longer. 13.6v float while the sun is out keeps the batteries ready for evening time and solar carries my daytime loads.