Although I would infer him to have already been aware of certain exceptions, e.g.:

If you and your opponent both know eachother to be skilled and masters of the way, then attempting the same tactic a third time becomes a different tactic; you are making an attack which your opponent would never expect you to try again.

It's a common failure mode of intermediate-level students of a competitive discipline to fall prey to the simplest tactics used by the weakest beginners, simply because they expect their opponent not to use said weak and simple tactics. For example, experienced chess players losing repeatedly to a complete beginner because they're used to playing against stronger and stronger opponents as they were gaining their experience. I've seen it happen often, and it's happened to me too.

ETA: I acknowledge that the example above isn't quite what is seen out there. What I had in mind was a one-off thing - of intermediate players, a "significant amount" (not the majority, but I'd guess "enough so that most experienced players have seen it happen more than once") go through a point at least once where they repeatedly lose against a player much less experienced than them, because of the reasons above. This second point is also debatable, but I think it's worth splitting and distinguishing between the two.