Couple of possible problems. First, you may be blowing the wax seal when you plunge, but the real concern is why do you have this frequent problem? Plunging is not going to do much good on a clogged drain line. That requires professional to auger the line clear to the street/septic. So my focus would be on the toilet. It may be you have an poor quality toilet. Early low flow toilets had serious clogging issues due to trying to use old designs with less water. Another reason for clogged toilets can be a foreign object that is wedged in the toilet trap and catches paper. Many things can cause this problem, but commonly found things are GI Joe type toys, toothbrushes, makeup cases, and the list goes on. Sometimes you can use a toilet auger to clear the trap, sometimes you have to go from the underside. What I'm suggesting then is that it is likely your toilet is clogging, and when you plunge, the pressure of the plunging blows the seal. Another possible problem would be that the toilet does not set on the flange as it should. Any movement of the toilet will break the wax seal. Wax is not like rubber, it will not return to the original shape. But, the latter would not account for the backup. Hope this gives you so ideas on where to start.