Yes, indeed it is a challenge. I tried to decrease my prednisone by 2.5 mg, going from 25 to 22.5 mg, but I had repeat symptoms. So, back to 25 mg. Then, I decreased by 1 mg decrements at a slow pace. What really helped though is that I was started on methotrexate and this allowed me to continue decreasing slowly by 1 mg amounts. This worked for me during a previous episode of PMR in 2018. Mind you, methotrexate has its own set of challenges and these are discussed in other blogs, but so far is tolerable. Here is the link to a good article from 2015 on the management of PMR and its by the American College of Rheumatology and European League against rheumatism. The flow chart shows that methotrexate can be considered when its difficult to wean off prednisone. Hope this helps
https://onlinelibrary.wiley.com/doi/epdf/10.1002/art.39333