I has been taught to do always the carburetor heater check with my left hand in the throttle and the right in the "lever?" (stick between legs) , ALWAYS looking at the engine rpm , I can't see the problem with the ice and high rpm, you can always roll the throttle, but it's also true that I haven't flown in icing conditions...
I think that there is no need for a rpm limiter , but I'm just a low time student
To my mind, if the pilot follows the checklist, they're safe, and it's incumbent on the school to teach well enough to avoid it - not only in the "this is what you do and don't do" but "this is the time you concentrate on one task" sort of stuff.
I think extacly the same...
A friend of mine , in the first hours almost had a overspeed but , as it should be he was with an instructor.
Regards.