ATP is one way to get multi time. After I went to ATP, I went back to the school where I got my private and now am their "main" multi-engine instructor. I exclusively teach instrument and multi. Next month getting a huge raise so I was making more than I would of at ATP, even more next month.
Another benefit to where I teach, my employer teaches me like family, I am respected, look upon for guidance, and treated like a human being.
Now with all that said, the biggest reason I am their "main" Multi guy is because I went to ATP and got the 140 hours of multi. It is pretty weird, we use the ATP training supplement and checklist, so even though I am not working for ATP, I teach the seminole as if we were at ATP. Well, with a few additions, like adding a few inches of manifold pressure and reducing a few inches during the governor check.
AND YES, I cut the engine with the fuel cutoff switch, and I even will shut off the RIGHT engine in flight!!!
Never could do that at ATP...