Has anyone done the 100 squats a day for 30 days?

My heart's in it, but my knees certainly aren't.
I would hurt myself just [i]thinking[/i] about it.

Tatsumi · 31-35, M

It's okay. Namely builds muscular endurance. There's metabolic burn up, aka the "burn" which is a factor for muscle growth, but not much overload, meaning not m7ch muscle growth. Focus on time under tension--no rest for the muscle at any point of the lift: constant work, constant burn, then pushing past the burn. Only way to get the best results. Still be good for you, though, either way.

It'll be good to keep you in shape, mixed with other stuff, but don't expect too much. Main thing with ex3rcise is pushing the envelope. After you can easily hit 100, you need to make it harder to get benefits. So, slowing down on the eccentric portion or the "down", exploding up faster, mixing in isometric "holds" at vsrious portions of the lift.

It's good. Not better than weights, but it can keep you in relatively good condition. Like I said, it'll mostly train muscular enduramce. Past 15 reps, you're working type 1A muscle fibers: they don't grow much, but they can last forever. Type 2 B fibers grow, and need more difficult, explosive or overload stimulus.