I didn't revise for my mock 'O' levels. Got good results, so did same for my actual exams and got A's in Maths and Physics.
I didn't do any work in French, cheating off my friend for six years and making one deliberate mistake each test and wasn't surprised to fail, getting a U for my French oral (Undefined... I spent most of my time speaking English saying "What was the word for...?" and then piecing the components together with the syntax I knew; essentially, I had a non-existent French vocabulary - the outside examiner was aghast).
I did the same for my, much harder 'A' levels (I really think we should all get 3 years to study for those) and wasn't surprised when I got a borderline E for Maths, etc. Concentrated on the areas I thought I could improve: Probability not Calculus (which is a total black art to me) and didn't fail in my mocks, so did the same for the real exams and got 4 A levels with really indifferent grades.
No surprise there.
I then did as I had planned and took a year out working on some paintings and then got into a Foundation Course in Art, which required me to have A levels and be over 18 for entry. Then I got into a 3 year Bachelor of Arts Degree Course in Fine Art (Painting, Drawing, Sculpture), which was what I had been waiting for the chance to do since the time I started my O levels.
Basically, my Secondary Education was a complete waste of time.
I work as a programmer (self-taught - there was no IT or ICT when I was at school).
I took the view that I would not revise because I wanted to be examined for what I had retained from conscientiously doing the course, not from some last gasp cramming. What I learnt I can still remember, although most of the really interesting stuff I got from watching TV as I liked to see men in 1970's kipper-ties explaining how to solve Quadratic equations. I think the important thing is to learn how to learn and to actually leave 'forced' education with a curiosity to fill in the gaps in one's knowledge. I'm not impressed by someone with a piece of paper with some embossed letters on it.