Apologies if this has been posted before.
If you've got kids whose idea of revision is cramming the night before and at the breakfast table on the morning of the exam you might find this site useful.
Getrevising.co.uk allows you to put in all your exam dates and create a timetable to suit you. You can put in all the times you have got commitments and it creates a timetable based on when the exam is and what times you can revise. Also allows preferences for some exams and if some exams need more revision than others. When I say "you" I obviously mean your DS or DD!
I've just done one for my DS. It looks a bit daunting but if you count each revision block as 30 or 40 minutes say it's not so bad.
It's at least a starting point even if they don't stick to it rigidly.