To me that sounds just plain unhealthy and distressing. You get a tiny dose of the thing you crave, then are kept away for two weeks wherein you struggle alone with the feelings and impulses that were stirred up in the session. I also think your therapist's suggestion to value the time you do have indicates some level of ignorance about how these things tend to go. As the paid clinician she ought to make sure that she is first doing no harm, rather than feeding you some it's-better-than-nothing logic.