However, it's always good to review things one has already learned. For me this usually leads to insights I haven't had before and a deeper understanding. Learnings seems to be an iterative process.
For example, I wouldn't say I really understood linear algebra until I went back and watched Gilbert Strang's lectures on iTunes U after my MS. Which is, of course, somewhat awkward, as I encountered many problems which required using it during my studies, but the only course I had on it was my freshmen Calc II class.
Basically I'd made it through years of schooling being able to make use of a tool without actually understanding the tool. If you'd asked me to solve any problem that required insight into LA rather than just application of common mechanical primitives, I probably did quite poorly.
: These lectures are fantastic by the way; they served as a good jumping off point for a bunch of other post-education math study for me.
As I said, reviewing material will probably lead to insights you haven't had before. If you've got spare time it's always a good idea to read a book on a topic like algorithms or a math book in order to get a deeper understanding, even if the book is just repeating things you already learned.