That is crazy
It is not quantity it is about quality, if the workload is to intense it can harm the good preperation that's gone before.
At this late stage just focus on DD weaker areas. The VR & maths in particular and work through it systematically. It is very difficut to make any huge strides in english at this late stage. Remember they will not know everything when they sit the exam, they are not robots!
Do not panic, keep calm and everything in perspective. Ensure whatever DD is working on she understands and it is sticking.
Best of luck