When and how to take a break from practice when it is going stagnant.

 They say "the difference between a rut and a grave is the depth".... Finding yourself frustrated or saddened with your current practice, some (as in the Zen tradition) would tell you, if you are frustrated with zazen, then sit in zazen. There is certainly something to that. Often you are at the precipice of some real insight or breakthrough when you notice you 'are not getting it' or are frustrated or what ever. However sometimes it is good to stop and do things differently . (It is also said, "The definition of insanity is continuing to do the same thing over and over and expect a different result." ) in Buddhism and the Buddha's teachings in general were good for all but some were not 'one size fits all' especially if you read into his direct teachings. He continually changed the guise of his lessons depending on the ability of the learner, using examples, direct lessons, simile, metaphor and the like. This is an important concept to adopt, maybe sitting (this or that way) is not for you? How have you changed your practice that helped you out? Have you found yourself against a wall? What did you do that worked? What didn't work?