One squeeze equals one bullet. I think the majority think the clip can be emptied with one squeeze.
Clip?
Aside from a small handful of very old M-16’s or smuggled/illegally modified rifles, all you can legally get in AR rifles is semi-automatic. One trigger pull, one shot. You can get a “bump firing” type of stock or device that will cause the recoil motion of the rifle to make your finger cycle the trigger automatically. It can also be done (with practice) by holding the rifle a certain way.
Here’s a home-made “bump board” for a semi-auto pistol: https://www.youtube.com/watch?v=nlFZOBiWRko