David, if you’ve had trouble getting off prednisone in the past then I’d recommend thinking smaller than your idea of alternating 5 mg and 2.5 mg. For example, you could try alternating 5 mg and 4 mg for a while, and then going to 4 mg per day.
If you have an underlying condition that the prednisone is treating then simply withdrawing the prednisone will fail. You need a proper diagnosis, and then a plan for how to treat it, ideally without steroids if that turns out to be possible. You may need a better doctor. If you have cuffitis then it would be best to start Canasa well before beginning a prednisone taper.
Even if steroids turn out to be necessary there are ways to reduce your systemic exposure. For example, rectal budesonide (Uceris) would focus the treatment where it’s needed, possibly reducing the effect on your bones and other organs.