Timing is the whole job
Almost every first-months disaster is a clock failure wearing a behaviour costume. The accident by the door was a missed after-nap trip. The biting at six in the evening is an overtired puppy who has been awake five hours. The refused dinner was a meal offered too soon after the last one.
Sit does not coach any of that. It puts the next thing on a real time — feed, crate, potty, sleep — and tells you what it is now, so the fifteen minutes in front of you have an answer that does not require you to have read anything.
The next fifteen minutes