OK. I'm not sure about all pizza places, just the ones I've had anything to do with. I like a sausage brand called LaScala's. For pizza, we use the standard Italian style/seasoned skinless bulk sausage. Outside of PizzaHut, and that was only for educational purposes, at everywhere I've ever been, we used our hands to put on the pieces/chunks of sausage. One hand holds a glob, the other hand, kept wet with sauce (keeps the meet from sticking and helps w/ speed), grabs a piece/chunk and puts it on. It's easier to put it on before the cheese because it sticks better, but different houses have their own styles. This has always been, in my experience, done by eye, no weight measure. There are different takes, in the eyes of great pizza guys, about the size and placement of these pieces/chunks. For me, the size of a regular martini olive is good with about 1 1/2 finger space in between each piece/chunk. Again, it's a visual thing. Too little is kinda cheap and too much takes over and can make your pizza an oil slick. All in all, if I had to put a reference # to the whole thing, I would say for a regular, large, thin, 2-person pizza, with only sausage, in Chicagoland, I would use the equivalent of 2 sandwhich links (+/-16").