This is biology-dependent. With CRTs, I could detect flicker all the way up to 85Hz* (where it vanished for me). Made it a real pain to find a good monitor.
* Hitachi 21" CRT which seemed enormous at the time
You are right. Perhaps I should've phrased it as "most people need..."
The Amiga interlace flicker was bothersome to me. When I got an Amiga 3000 with the built in deinterlacer / flicker fixer, it was like night and day...
* Hitachi 21" CRT which seemed enormous at the time