“Think of a typical full-time worker, who's in the office from nine to five daily, but takes thirty minutes for lunch, leaves an hour early on Friday, and comes in an hour late on Tuesday due to a dental appointment. That puts her at 35.5 hours for the week. One errand tacked on to the end of lunch one day or a longish midmorning break will pull her under that thirty-five-hour threshold that defines "full time.”