I did my PPL on 0-200 engined C150s off grass. We were taught the usual carb heat use and we knew carb heat was an ever-present threat. But I don't recall any plummetting as a result, despite all these neophytes driving around the skies behind 0-200s.
I think the C60 in the L4 Cub I flew was worse for carb ice. And our Yak52 didn't even have a conventional carb (single point fuel injection into the blower) but would readily ice up on the ground on damp days. I once opened the throttle to take off, and the engine stopped!