As I understand it, friction brake use is the same no matter what the regen setting.
"Regen setting" is misnamed, it just affects how much the lifting of the accelerator slows the car. Using the brake pedal, does the same thing as lifting your foot off. Just watch the power meter and you'll see this is so.
The friction brakes only come into use when the battery can't take any more current.
So braking hard to get the power meter over -20, or when battery is greater than 95% charge.
Don't forget, this is all computer controlled.
Lifting foot or pressing brake, just tells the computer you want to slow down.
Computer will then use regen to slow, until battery capacity is reached, then apply the friction brakes.
Go with the regen level that suits your style of driving best, it won't make any difference to regen levels or friction brake use.