I called Nissan to ask about this. I've heard posts from folks using the 20%-80% rule, others that time is perfectly so that it only stays at 100% for a short while, and other that charge all the time without any regard to anything!!!!
I have a 2018 Leaf, so the battery chemistry is probably different from the 30 kw/h versions.
So....I called Nissan and asked them. They said that high heat is the most important factor when talking about battery longevity. They said that if it's hot out, park in the shade. Also, turn on the A/C in the car 5-10 minutes before you get into the car, when it's outside. It doesn't completely cool the battery, but it helps.
They also said to let it run down to 30-40%, and recharge then. 20%, 30%, 40%.....those levels ( In other words, don't drive to the store and recharge it when it's 90%! Also, don't let it run down to 5% either!!!)
The theory is that it reduces the number of charging cycles.
With all that being said about charging cycles, etc......far and away the most important thing is to try and keep it out of the full sun.
My plan is to follow those instructions, and in 2023, I will let everybody know how this plan worked out!!!! When it's low, I am going to charge it to 100%, and I am not going to time it, unless I switch to a power plan that is less expensive overnight.