Markus, I don't think you can just look at daily mileage and make conclusions about "pushing too hard." And, along those lines, why do you label her recent 60+ mile days a "push"? Couldn't it just be she has been giving a consistent daily effort from the very beginning? She has kept her daily "time on feet" to 13-14 hours, with very little variation throughout.
I would attribute the recent uptick in mileage to (1) the fact the weather is now perfect for running (50s-60s with no rain, as opposed to the heat of California, and the cold/blizzard conditions of Utah/Colorado); (2) the flat terrain of Big 10 Country (i.e., Nebraska and the "Three Eyes" she is about to reach (Iowa, Illinois, and Indiana), as opposed to the climb in Yosemite and up and over the Rocky Mtns., and (3) the warm outpouring of support she's receiving in Nebraska (yesterday, about 15 runners met her in Center City, and she's had people drop in all across the state . . . I'm sure you know how much that can help!).
Rest-assured, Sandy is being advised the whole way by the absolute best in the business (i.e., the World Record Holder (Pete) and the Masters' Record Holder (Marsh))!
While, yes, Sandy is relatively-new to the sport of ultrarunning, she's accomplished a lot in the past two years, highlighted by her win at Badwater this year, against -- easily -- the best women's field ever assembled at the race. (Look up the career of Szilvia Lubics for proof of that fact...)
I told you guys near the beginning of this quest that Sandy was going to surprise a LOT of people out there. I would not bet against her.