I don't think there is an "entitlement" to time to mark, but with work-life balance in mind, I'd expect to have some. Have you asked your Headteacher for some extra time? In my school, the Y2 teachers draw up a timetable and then tell me what supply they need. They have supply teachers in to take class when they are withdrawing groups for testing, then to release them to mark some of the papers(usually reading and writing) and then time to moderate each others marking. It's really important that they make accurate assessments as future Y6 targets are built on them. Because I trust the Y2, I take their recommendations and run with them. In fact, because they want to limit the effect of having different teachers on their class, I sometimes have to persuade them to have more time than they've asked for.