Neither is better; each has its own functions. The concentrated work beforehand is necessary to assimilate the knowledge and establish mental connections. If you cannot manage that then you should not be studying that subject anyway; you will never achieve anything better than memorisation, and that hardly counts as study for any worthwhile subject.

Any key points, such as particular values, terms, mnemonics, or lines of thought in derivations, should be noted, ready for last-minute revision. If you have a very bad short term memory, then memorise the key points at the last minute and write them down in some legal position on the exam paper at once when you enter the exam room. (The value of pi is... The atomic mass of...)

Even if you have no need for that particular tip, running over those key points that you have noted at the last moment, even if you cannot take them into the exam room with you, are of crucial value in organising your thoughts and making sure that the key concepts are fresh in your recent memory. This is no substitute for the serious business of study, but it is magically valuable for access.

You really should not be doing either of these. Just think about the number hours that you have spent on a subject over a year and then think how much 4 hours is going to add to that.

The big mistake is to think that revision should come at the end of a course. The best way to handle revision is to make it something that you do continuously throughout the year. If you can keep something in the front of your mind all year long you will come to a sound understanding rather than just having a short term grip on a very few facts.

They say that success comes before work only in a dictionary. I'm afraid it's pretty well true. The secret to successful study is organisation and hard work. Learn the course content as you go through the year and make sure you understand it all - I mean actually understand it, get it into your head so that you can visualise all the processes involved. When it comes to revision all you have to do is resurrect that understanding. Get a good night's sleep and then do the exam.

If learning is for you, then you must also learn to love it for its own sake. Don't make a chore of it.