For some students the retention of subject information is good throughout the year, and therefore they won't need to revise for more than a couple of hours each day. However, there are those that struggle either because they haven't applied themselves effectively throughout the year or because they genuinely find learning harder than other students.
The apps reviewed are excellent additional revision resources and learning aids and a lot of them are totally free. I would recommend that both students and their parents get to grips with what's out there to help with revision planning, note-taking, data storage, grammar aids and exam count downs.