There are several hundred threads on the subject.
Theoretically, generally charging to about 80% will extend the life of your battery, with occasional full charges so the cells can balance. This is especially true if you don't use the bike regularly. Leaving it fully charged for a period of time (weeks/months) can reduce the lifespan.
But it depends what you want from the bike, how often and far you ride and how obsessed you might be with extending your battery life.
More importantly. Don't charge the battery if its really cold - that won't do it any good. Don't charge it when it's really warm straigth after a hard ride - that won't do it any good. Don't ride it hard if the battery is really cold if you left it outside for instance, it will work, but be inefficient and won't do it any good.
If you know you'll get 2 or 3 days out of a charge based on similarity between rides, then fine, you can do that.
A "charge cycle" is basically a completely flattened battery charged to full again. if you do that as 0-100% in one charge or 5 charges of 20% - that's one charge cycle.
Lots of people have meticulous charge routines based on when they think they'll next ride. Lots of people just ride, let it cool off, charge it to full then get it out and ride it.
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