When I first started working as a flying instructor, pulling the mixture was the way the CFI wanted us to "fail" the engine for a forced approach. One day early in my instructing career, I was out with a new student and we ended up doing 2 full forced approached exercises. I felt that one more would be a good way to solidify the lesson but we were out of time so we went back home. After parking the aircraft the student went to shut down. He pulled out the mixture control and the engine died, but the knob did not stop at the usual spot and the student ended up pulling 6 inches of loose cable out.
. The cable had failed at the carburetor rod end and it was only very good luck that it had not failed when we were doing the forced approach exercises.....
The next day a memorandum form the CFI required engine failures only be initiated by closing the throttle...........