How about an hour or two of revision a night? Too much? Not enough?
Of revision itself an hour or two a night consistently is quite dense (remember this is revision, not including the assignments, if you do practicals you may have pre and post practical tests, ILTs, assuming you pick Chemistry you will have CHEMCALs and have to read the practical before the class for every subject you do with practicals, it doesn't include getting used to the system, or depending on the course/subject other features, printing out lecture material etc. I don't know if pre-reading classifies as revision, but I don't think so too).
There's no set time, it's if you have time left over you do revision. Because as University students you still have to 'have a life' - socialise, join groups, make friends and so forth. Luckily the tutorials, lectures and practicals* provide revision streams. There is a lot of room for revision during the last few lectures for some subjects where they do revision lectures (out of normal class time), or even spend the last few lectures of the course reviewing, mid-semester break, SWOTVAC, weekends, when you don't have practicals, or when you've covered all the material in the lectures and tutorials and practicals in general. The tests throughout the year or weekly quizzes make sure you learn the material anyway, and many are identical to the exam, so once you've done those tests, in the future it's quick to revise them.
Regarding the practicals it is arguable that only some subjects try to make the practicals directly related to the course.