I think one thing that most people do not understand at the beginning, and might not realize for years in some Traditional Martial Arts, is that striking requires energy and will wear you out, even more so in a scenario where uncertainty means you can't set yourself to do one technique over and over again. A classic example in popular culture is Muhammad Ali's "rope-a-dope" defense where he let attackers wear themselves out while he found ways to absorb their blows with less damage. More often, I've seen TMA practitioners learn that lesson when pointed to a heavy bag and told to just attack it continuously for a few minutes. It does wear you out, and in an actual fight scenario, the added required strain of being prepared to dodge, block, or strike at a moment's notice just adds to it. And, not always obvious to people, missed or pulled strikes are almost as exhausting as ones that you land "with full force" because you need to exert just as much force, just in different ways.
Even in MMA circles, it's not uncommon, especially at the heavier weights, to see new participants "gassing out" pretty quickly.
Truthfully, this is as much a matter of cardio as tactics, but learning to strike selectively, to husband your energy for when you need to throw that flurry of blows, and how to recover while still defending yourself if that flurry doesn't work, is something you need to learn.
