"basically wean down until you get sick, increase when you get sick"

That sums it up nicely!

Taper prednisone slowly until you feel lethargic and your body aches from symptoms of adrenal insufficiency. That assumes you haven't already had a flare of PMR. With a low cortisol level you won't be able to regulate your inflammation levels very well. Since you won't know if you are having a PMR flare or symptoms of adrenal insufficiency and possibly both, increase your prednisone dose again until you feel better. Repeat this process and try to taper your prednisone dose again. If at first you don't succeed try and try again.

The only thing that stopped this cycle for me was a different treatment that stopped me from having PMR flares. My treatment with a biologic which didn't suppress my adrenal function allowed me to stay on low dose (3 mg or less) of prednisone. This allowed my adrenal function to gradually improve in 6 months time. The whole process took a year to have an "adequate" cortisol level. Then and only then could I discontinue prednisone while still on the biologic. This compares to the 12 years that I tried to taper off prednisone with but mostly without other ineffective steroid sparring medications.

For some people, depending on how long they have taken prednisone, their adrenal function may never improve. On the bright side, for most people, their adrenal function will eventually improve assuming their prednisone dose is low enough.

Getting off prednisone is the best way to improve your adrenal function and regain an adequate cortisol level. Otherwise it is a Catch-22.