The only time our TLs and ETLs "coach" on the floor is when they are telling people they did something incorrectly and have to demonstrate the correct way to do it. As commiecorvus said, nobody should get chewed out on the floor in front of people. Formal coachings, at my store, are done in the ETL-HR's office. Because we also have an HR office, used for HR things, people have joked about putting a sign that says "Lasciate ogni speranza, voi ch'entrate" (Abandon hope, all ye who enter here) on the door of the ETL-HR's office.
To summarize, simple "you did this wrong, here is the correct way to do it" is basically training and that happens on the floor all the time. Something like "you did x, y, and z wrong yesterday and the morning team had to spend so much time fixing it" should not happen on the floor. A formal coaching where you sign a paper does not happen on the floor at all.