A lot, I'd say even most people in Germanys long term unemployment scheme which are not already working part time (Aufstocker) have severe mental and physical health problems. More pressure isn't going to help those people but it's the current Government's shtick.

I'd say UBI would make it easier to find people working in demanding jobs because you could to them part time, so they don't wear you down as much. It's much easier to work as a nurse for 20 hours a week.