I have posted this before, more than once, but I have found that by varying the amount of PM I take, I can influence the amount of growing pains I get.
My routine is that I take 3 x500mgPM, twice a day for a few days, then drop down to 2x500mg twice a day for about 3 weeks, then drop to 1x500mg twice a day for a few days, then go straight up to 3x 500mg twice day for a few days, and so on. This very roughly mimics the general pattern of natural estrogen production. I have found that I tend to get increased pains both sides of that peak, as though my body reacts to the change in levels, rather than the actual dose.
This may tie in to some extent with what Waihaka has said about not allowing the body to get too used to a constant level and going into negative feedback.
Of course the actual hormone production cycles are far more complex than that, and I don't have any progesterone in my routine either. No doubt Isabelle will be able to say far more than I, on this subject.