When I worked as a church secretary they wanted me there 5 mornings a week, 9 - 12. I was responsible for doing the weekly bulletin, the monthly newsletter, answering the phone, dealing with the food pantry, and a few other general duties.
Many times there was "nothing to do." They had a weekly cleaning crew so there wasn't any cleaning to do. I remember organizing the cabinets, rearranging the office furniture, etc. but there were some times where I was literally twiddling my thumbs. I remember discussing it with the church pastor, and he said if I brought a book with me he didn't care if I read it when there was literally nothing to be done. I could also write a letter if I chose to, he didn't care. I felt bad when there was nothing to do, but they wanted me there if only to answer the phone.
Then when I worked as a waitress there was always cleaning to do when we had time, even just wiping down the menus, pulling everything out from beneath the counters and wiping them down, washing windows, etc. Usually this stuff happened during the slow times between breakfast and lunch, and lunch and dinner. The hours I worked were generally quite busy so we didn't have much, if any, time for cleaning.