Crews come in twice a year (typically). Some events are "no jeopardy" such as the LOFT/MT, but all the "evals", such as the Maneuver Validation and the Line Oriented Evaluation are jeopardy in the respect that you can "fail". However, it takes more than one "unsat" on the same "task" in the same "event" for the event to be considered a failure.
There is much more to it than this, however. SFAR 58 is the regulation which provides for the creation of an AQP and AC 120-54 has all the requirements which an AQP must meet. These are good references for information on the program.
Again, if you need something more specific, let me know and I can tell you how it's done here. But, each company has their own individual AQP that is approved, and ultimately this drives what and how they will do it. Just because one company does it one way does not mean that is how all companies do it...but all companies are governed by the basics of SFAR 58 and AC 120-54.