How was your body afterwards? And how flaky was the plaster to start with? The stuff that's come off already was fairly loose but I've already hammered my hand twice on the other stuff. How large a space did you clear by hand and how long did it take?
Probably 5 square meters over various years. It's not much fun and it takes a long time. Some was pretty tough - when I did the bathroom tiles they seemed to be concreted to the wall but it came off with a bit of a fight.
A power tool will probably make light work of it.
That's what worked for me