When I was a supervisor I had to reject a ton of PTO requests because we only had so many slots available in a day and our scheduling lady wouldn't work with me AT ALL. The only thing I could tell them was they can switch shifts with one of their coworkers or "You, know, you only have x points against your attendance and consecutive days off still only count as 1....". We had a lot more missed days due to people taking full advantage of the attendance policy than we would if we'd just scheduled them off the day they asked for. One of many reasons I got out of that job asap.