Just out of curiosity, when you have a substitute in your room, do you expect them to mark some/all off the work from that day? If so, do you explicitly ask them to do it in your day plans, or do you assume that it will get done on your prep period? I remember when I was a new teacher and substituting, I was never sure whether the teachers wanted me to mark the work that we were doing. On rare occasions the teacher would ask that I mark "____" during the prep block, but most of the time there was nothing mentioned. I didn't want to seem lazy by not using the prep block to do some work, but I also didn't know if the teacher wanted it marked. I know sometimes teachers have a certain way they like to assess work, or maybe they like to do peer assessing, etc. So as a rule of thumb, if it was something very straightforward, such as a basic addition sheet for example, I would usually mark it without being asked. But if it was something that could have different answers or marking schemes, I left it alone to be safe.