[byw]

I wonder for drivers who drove with regen-only for too long, do they lose the reflex to hit the brake?

[recursive]

No. I do fine when I end up in a rental ICE. In my EV, I still use the brake when I need more stopping. If I zone out and forget I don't have regen, at some point, I'll notice I'm not slowing enough, and hit the brake, just like I would normally.