So, charging overnight should be to perhaps only 60% before starting a long downhill trip - so that will have sufficient Regen-current storage spacenin the Battery?
Maybe THAT is the reason they suggest charging to only 80%, to "hide" the fact that you will not have any Regen for the first 16 (to 20 or so) miles of your 100%-charged commute?
To wait until you are fully down two bars (16 or 17 percent) before "giving" us ANY Regen ... is a poor choice, I think.
Taking Regen away abruptly, if the LEAF actually does that at 83%, would be very poor. A gradual decrease in Regen, along with the display of a big flashing red "Losing Regen" warning, and then a "No Regen" status, would be much better.