I am typically on a 5mg taper, but in the past I have been on much higher amounts where I tapered larger does than you mention. Right now, I'm doing something different (also with my dr's direction, of course) to get off pred and to try something else. My point being, what's typical isn't always the only way.
If she is concerned about it, there's no reason not to give a call to her doctor, in my opinion. I would certainly do what the doctors says over what you might think is typical. Discussing this with the doc might allay some of her fears and maybe help you better understand the course your doctor chose.
And, not to sound preachy, but try to help her relax. She might not like pred - few of us do - but she's on it presumably because the her doctor deemed that the downsides outweigh the relief I hope she's getting from it. :hug: