I taught Maths for 15 years. I always told my ablest students the truth about revision. I told them that I'd never revised for a single minute for any of my 9 O-levels or 3 A-levels. I didn't revise for the 'Principles of Education' element of my teaching certificate. I didn't revise for the 'Mathematics' element. I had a few (unnecessary) moments of panic and spent a whole 45 minutes revising for the 'Physics' component. I then didn't do any revision whatsoever for my degree in 'Mathematics as a Double Subject'.
If you've really paid attention to what you've been taught, revision is completely pointless!!!!
Chris