leeosteo, there are studies. I haven't looked at them for while; they must be dated. I spoke to a pathologist who said that bisphosphonates adhere in irregular patterns unrelated to bone weakness. I've read ten years for zolendronate, two years for risidronate. Those being the highest and lowest.
The waning of Forteo is gradual. Signaling from osteoblast activity raises osteoclast production.
I suspect that there is a point at eight months to one year where an interlude without Forteo would restore balance. My guess is that one month without any medication is best. That is mainly from looking at charts showing the decrease in bmd after cessation of Forteo. I did have a month without Forteo (lost pens) at around ten months. I can report a larger drop in osteoclasts (CTX) than osteoblasts (P1NP) indicating (at least to me) improved balance.
Behind this is the presumption that bone remodeling has a best CTX/P1NP ratio.
Beyond your question is the additional assumption that while the ratio is important, a higher number of the osteoblast-osteoclast coupling is needed when we have osteoporosis.
I've not looked at Great Bones. From comments on Mayo Connect, I could wish that the declarations had more depth. Why does the chiropractor recommend against risidronate. Is it the very reason the bone expert recommends it if you plan to retake Forteo or Tymlos. Why does Forteo wane after 18 months.
Mind, though, that there are extremely intelligent physicians who say that you can't use CTX and P1NP in relation to each other. Their only use might be in relation to themselves prior and post pharmaceutical intervention.
Will you be using bone markers?
I'll look for citations hoping some other poster beats me to a recent publication. I think my sources are 2008.