YES! It's been a while, but you suddenly reminded me of a similar arrangement we had for fetching coffee. We also used an elaborate Excel spreadsheet that took into account how much coffee you drank, the percentage of part-time (old geezers get to work less hours for the same pay, so it's only fair that they get to fetch less coffee, right?), off-days, holidays, etcetera. I'm pretty sure it was the most used spreadsheet of the entire department.