I kind of wonder if the tipping point of "exponential decay" might be where a battery starts being charged and discharged more often to reach daily range and maybe outside the 20-80% window you need for a healthy battery.

In other words, if a battery is new and has 200 miles range, but is driven 100 miles a day, it will stay between 20-80% charge each day when charging.

but at 80% capacity, 160 miles range, it must be either charged above 80% or discharged below 20% each day which is unhealthy for the battery. (either 80%->17% or 83%->20%)

as soon as it starts getting out of healthy range I can see how it can degrade faster.

But cars that stay in that range will have a much longer lifespan.

As another comment mentioned, the cited studies are more about how the battery chemistry changes over time, not how people use the EV. That said, EV manufacturers definitely care about driver habits too, since it affects warranty claims and how they configure their battery management systems.

I think modern EVs are set up to charge to a certain percentage of capacity rather than a specific range, kind of like how smartphones do it.

Your point about depth of discharge ( 80%->17% ) makes sense though, since the battery system can't really control someone's driving routine.