Revision is about 'training for the exam' - being in 'top condition' for the challenge that the exam sets. It's about having the key facts at one's fingertips. What are the appropriate legal rules to solve the problem? What are the key arguments around central ideas in the law? What are the key cases in a particular area? It is NOT about memorisation for the sake of memorisations - it is about marshalling the resources you will deploy in the exam room.
Answering exam questions is not about dumping a load of facts, cases and slogans on a piece of paper - it's about marshalling them TO ANSWER THE SPECIFIC QUESTION SET.
So you do need to be able to
- use key cases to advance and/or prove the argument you are making
- set out - and EVALUATE - key arguments (for example about the level of 'Separation of Powers in the UK Constitutional System' or 'balancing conflicting rights arising from the European Convention on Human Rights')
- solve key problems (for example, assess whether a certain set of facts could give rise to a successful Judicial review claim, or a prosecution for a particular offence.)
Single facts, or single cases, are not by themselves key to success - it is the relationships between them.
Rigidity is an enemy of success. I've read many an exam answer which is little more than the dumping of all the facts the student can remember about the subject. That is not the way to success. As stated above, success comes from being able to effectively deploy your knowledge and understanding to answering the specific questions set.