Suppose you push to your opponent, and he has trouble attacking it. Licking your lips, you push to him over and over and he keeps missing. It seems a winning tactic, right?
Often it is. But sometimes all you are doing is warming up the opponent's seeming weakness and turning it into a strength. It depends on the opponent, but if he's able to loop or otherwise attack some of your pushes, if you give him enough, he'll probably get better, and then that big tactical strength you had is gone. Basically, you are warming up the opponent until that weakness vanishes, and now you have to find a different way to win. The same is true if you have a serve that gives him trouble and you overuse it until he can return it - and thereby losing that advantage. The same is true of most other successful tactics.
Instead, when you find such a weakness in an opponent, space it out so he can't adjust, thereby taking away the tactical advantage you had. Come back to it regularly and at critical points, unless you think he's expecting and waiting on it. But that's usually not the case - usually it's best to come back to what works, even if the opponent might expect it. With experience, you'll gain the judgement of when and how often you should pound your opponent's weaknesses!