Horses are not futurists. They can’t see into the future or read our minds and intentions. So when we ask a horse for something the very first time, they don’t know if or even when it will ever stop.
Horses are an enigma for everybody (even if people don't know it). We can’t possibly know or understand everything that goes on inside their head. We can take a guess and hope we guess right sometimes. But we have no right or basis to claim certainty because we don’t know how much we don’t know.
Nowadays every man and his dog talks about when a horse licks and chews or doesn’t. People point out when a horse yawns or blinks or changes the position of their ears or swings their tail. There are so many tiny observations to make that tell a tale about the emotional and mental state of a horse.