The instructor must keep the plane at a point where he (the instructor) can still have a high confidence of saving the plane. Different instructors will have different thresholds for when he takes over. The guy you are flying with may not be as experienced a flyer as another instructor also. Let him decide what he, and you, are capable of. Your plane will last longer and he will gradually give you more latitude. Remember also that it is possible for you to do structural damage in your recovery attempts.