The start dose for PMR varies from country to country with the US most often starting at 20mg and Australia, where I am, starts at 15mg. An Italian study (2011) found that 78% of people started on 12.5mg responded well, but effectiveness depended on the weight of the person with heavier people needing to start on 15mg.
I can't yet post links. Title is "The correct prednisone starting dose in polymyalgia rheumatica is related to body weight but not to disease severity".

I think I would have struggled more with the reductions above 10mg if started on a higher dose. Also, I ignored the directive to stay on 15mg for a month, knowing that in the first 2-3wks of prednisolone treatment the dose can be reduced more quickly without adverse effects. So I dropped as much as I could in those first 2-3wks (15mg down to 11.5mg) to get a head start on reductions.