Per the "flip once" theory, a steak should only be flipped once during cooking, as frequent flipping prevents a good sear and keeps the meat’s middle part from cooking properly.
However, flipping a steak frequently throughout cooking helps the meat maintain a steady medium temperature. It also helps the steak cook evenly on both sides faster.
Some argue that frequent flipping causes the meat to stick to the grill, but that shouldn't be an issue if the heat is high enough when you initially place the steak on the grates.
Flipping a steak only once exposes one side of the meat to the grill’s heat longer, leading to unevenly cooked steak with pink meat on the inside and well-done meat on the outside.
If you're going for medium rare and want your steak cooked that way throughout and not just in the center, your chances of obtaining it are much higher with continuous flips.
Frequent flips work for all beef cuts, be it arrachera, ribeye, New York strip, or tenderloins. Flipping a steak once isn’t bad, but it's not the sole way to cook a great steak.