My wife is onboard for the second opinion and I will be there.
I had an acquaintance that went through the Mohs' surgery. They had him on the table for quite a while and would remove some and send it to pathology and then cut some more. Sounded kind of brutal but obviously necessary. I'm an old guy too, nearly 73.
Normally, tissue samples are processed over a few hours, creating a solid paraffin block that can be sliced to just a few microns thick, stained, and mounted to a glass slide, often given to a pathologist to "read" under their microscope the next day.
A frozen section speeds up the process by flash freezing the sample while the patient is on the operating table. It still yields slides for a pathologist to look at, but the whole process takes a fraction of the time. It helps to insure that the whole lesion is removed by looking at the edges of it. It sounds like a long ordeal for the patient, but they're just sleeping. The surgeon and anesthesiologist and their staff can get a little impatient sometimes as they wait, but it's crunch time for the pathologist and their staff.
My wife was a surgical pathologist. (until covid came along and forced an early retirement) Frozen sections were one of the more stressful parts of her job. Her decisions directed the course of treatment, so an incorrect diagnosis could produce a very negative outcome. Missing a malignancy (cancer) leaves the patient to go on untreated, calling something cancer (when it's benign) may lead to unnecessary surgery, radiation, chemo, etc.
With a normal biopsy, if you got a tough or unusual case, you could research it a bit, show it to a colleague, or send it to an expert. A frozen is a much more pressing timeline.
It sounds like they caught it early and she should do just fine. Hopefully my little background view helps you to not freak out going by the clock and how long she's in the OR. If you have questions about the pathology report, reach out and ask. (them or my wife) My wife actually enjoyed meeting people and explaining things. (but maybe that's just her)