The release is more important than the pressure in horse training because it is the release — not the pressure — that carries the information. Pressure tells the horse something is being asked. The release tells the horse what the correct answer was. A trainer who applies clear, appropriate pressure but releases at the wrong moment — a half-second after the horse has already moved away from the correct response back toward a wrong one — is teaching the horse something different from what was intended, regardless of how well the pressure itself was applied.
This is why timing is the most critical skill in horse training and the hardest one to develop. The horse's brain connects the most recent event before the release to the release itself — meaning the last thing the horse did before the pressure stopped is what it will offer again next time. If the horse bends its neck to the left and then straightens, and the release comes after the straightening, the horse learns that straightening is correct. If the release comes during the bend, the horse learns that bending is correct. The behavior the release follows is the behavior that gets reinforced.
The quality of the release matters as much as its timing. A full, genuine release — complete removal of all pressure, a moment of rest, perhaps a quiet word or scratch — communicates clearly that what just happened was exactly right. A partial release — maintaining some residual tension, not quite letting go — leaves the horse uncertain and searching. The cleaner and more complete the release, the faster the horse learns, because the information it carries is unambiguous.
Warwick Schiller describes the release as the horse's reward not just for doing the right thing but for trying — the try, however imperfect, earns the release, and the release builds the try. This emphasis on rewarding the try before the horse has perfected the response is what produces horses that are actively engaged in finding the answer rather than waiting to be forced into it.