Question Deep Discharging - How to and how often?

I have seen various posts about deep discharging lithium batteries, and I am curious about how to and how often it should be done.

Here is my set up:

No commercial power - completely off grid.

1 X 6000XP

2 X Indoor wall mount batteries

1 X 14KW Gen

18 panels - 2 arrays 9 panels each approximately 7.3 KW solar

I am now at a point where my batteries will top off by noon and house will ride until about 5:00

In the morning, I will only be down to about 85%

As the days get longer, I am expecting that I will only drop to mid or low 90's percent and bee topped off by 9 or 10 in the morning.

This is nice as I can run on solar the remainder of the day until nighttime.

So, how do I discharge down to 20% and charge back up to 100% safely and without much interaction?  ( I am not always here (yet )

Any chance I am missing some "maintenance" setting that says every X days force discharge (or I guess it would be prevent charge) down to XX%

Any suggestions on the best practices for doing this?

Also, can anyone explain why it is needed?

Thanks,

JB