In general charging to 80% and recharging at about 30% will give the most cycles.
But there is much more to this, keeping the temperature cool, not punishing the cells on high charge or discharge rate, storing the cells around 50% when not used for long periods and so forth.
All that said cells are not expensive so some may see no point in babying them, but conversely if you do see the point then you can put in the work and have your cells live a long time.
As for citations for all this, i don’t have any off the top of my head, but you can run what i have said through the google and read through the results.
There was also another thread recently on BLF about this, if anyone remembers the title of it a link would save a lot of repeat keystrokes.
I charge my cells on the lowest setting and don’t leave them in hot/cold environments. Otherwise, they don’t get babied. I feel like they’re going to degrade over time either way so no point in worrying.