Okay, I'm not sure I understand your answer, but here is how the typical MMI is run (time limits will vary):
1) Two minutes to present the scenario (read in silence).
2) Five to eight minutes to interact. Assuming a typical behavior-based scenario with 1 evaluator*, I normally would assign the evaluator two to three additional follow-up questions that must also be answered. Consequently, each station should have the known scenario plus at least one reflection follow-up question that you must answer for full credit (depending on the rubric or instructions to the evaluator).
* This excludes any "team-based"/collaboration scenarios. For example (not from an actual MMI, but hopefully more entertaining):
Usually, this involves one candidate giving instructions to another candidate regarding a task or describing something with verbal instructions only. Two evaluators are observing (one for each candidate). Usually one is drawing or doing something like tying knots.