If ask her to prioritize she will say everything needs to get done.
Ok this is a big fat
red flag to me. Always has been. Always will be.
Simply put, "Everything needs to get done" is NOT the answer to a question regarding priorities.
In a previous post about a similar topic, I suggested what I did with my boss at the time.
I suggest the priorities. As in, "OK Boss. I'll start by calling about A, then move on to finishing the spreadsheet for B, and then work on the mailing for C."
You boss may realize then that the spreadsheet for B is more important than the call about A and will (hopefully) then tell you so. But by forcing a priority, that at least gives your boss a framework in which to operate, instead of panicking that "it all needs to get done."