Yes, once and done but depends on a number of factors. First as to application. I was the first to use at my proton beam radiation center and I had the RO put on. So my field was smaller than with standard radiation and I had lumpectomy with no nodal involvement. Took maybe 10 minutes. Husband watched this plus the YouTube and was able to improve on original application. Sweat and water will cause the film to lift and removing can hurt our tender radiated skin. So I skipped sweaty exercise and resorted to daily sponge baths to keep the area dry. The film also helps because it keeps your skin from rubbing against clothing! I took mine off about 1 and a half weeks after radiation was finished. The FB group is really helpful, ask away! One other thing, you do not need the film on for mapping.
Mayo’s sheets are expensive and you don’t get many. I got mine from Medical Warehoue in. Canada. FB said it was on sale at this time. It takes longer but for an additional charge they will expedite. Hope this helps.