Hasn't happened in 26 years yet so I assume it won't. I had a new roof installed last year and unbeknown to me they ripped up the gutter guards with the old roof and threw them into the dumpster. Back a few months when we got the heavy rains what your describing is exactly what happened. Even got water into my basement for the first time. I cleaned the gutters and installed the guards and everything's been hunky dory since.