Sheble's
I got my ATP at Sheble's in 1989 when he was still in Blythe, California. You have to pass your ATP written beforehand, of course.
I reported late Sunday afternoon, took a sim and an oral with my instructor, came back early the next morning, took one fight in the Duchess, met with the examiner, took an "oral" (all five minutes' worth), a sim and a flight, another sim, and was out about noon on Monday. Maybe the routine has changed in thirteen years, but I doubt it.
The place was very informal. He had cats running around the hangars. Not a necktie in sight. It was definitely not your father's flight school.
It pays to be prepared. I practiced the BLH approaches in the sim for about ten hours. I had a friend who got his multi there (all three hours' worth) and he provided me the Duchess gouge.
Hope that helps some more.
In the old days of aviation, the Airline Transport "rating" was called an ATR, for Airline Transport Rating. It is a faux pas nowadays to call what is now the ATP certificate a rating. Some countries call the paper authorizations they issue pilots to fly aircraft licenses, e.g. Canada and the U.K., but not here in the U.S. They are certificates here.