A common mistake I've seen is for a player to find something that seems to work in a match, and then go to the well too often - they use that tactic so often that the opponent gets used to it. This is a double-whammy - if you do this, not only have you turned an opponent's weakness into a strength, but you have to almost start from scratch in figuring out how to tactically beat this player.
This is why it's important to find more than one way to beat an opponent. There might be one primary tactic, but you need secondary ones as well. Try to match your strengths to the opponent’s weaknesses. Or match your strengths against their "average" shots, or your "average" shots against their weaknesses. But you do want to find the best tactic that works, and use it as often as you can get away with it.
With experience, players develop the instinct on how often they can get away with a tactic that works. They also learn the difference between something the opponent simply can't do effectively, and something the opponent will learn to do effectively if given enough chances.