I do as much as I need to until I've finished what I planned to do. I have a big list of all the days of the easter holidays and then next to it I have what I need to do. For example,
Monday 2nd: Biology Module 1, Chemistry Module 1, Biology past paper, Chemistry past paper.
Tuesday 3rd: Psychology Module 2, Physics Module 1, Psychology past paper, Physics past paper.
Doing two subjects a day gives me a bit of variation rather than doing the same subjects every day.