time off - What is the perception of students who take a gap year between their graduation and starting graduate school?

I am an undergraduate mathematics major, entering my fourth year. I plan on applying to graduate school, but I have not yet taken the GRE exams, and there a few key courses (Topology and Algebra in particular) that I have not taken yet, so I am hesitant to take the Advanced Math GRE too soon. (If you're wondering why I haven't taken Topology and Algebra yet, it's because I was trying to secure a CS degree, which sidetracked my mathematical studies last year. It was a healthy branching out experience, and one that helped me realize my true academic passion.)

My main question: what is the perception of students who take a gap year between their graduation and starting graduate school?

I think I will take the GRE tests this fall, a) for practice and b) if I score high, then I might as well apply sooner rather than later. However, I ask this question to gauge how much energy I should put into preparing for the tests this fall. If I hear, "You should really do your best to avoid any gap in your education," then I will work my butt off in preparation for the tests. But if I hear, "It's totally okay take a gap year before going into graduate school," then I would give myself more freedom in terms of my non-standardized-exam studies, extracurriculars, and in general social activities. I figure the answer to this question won't be as cut-and-dry as I hope, but any advice would be appreciated!

Just to clarify, my gap year would not consist of me sitting at my desk taking practice GRE exams all day... That would be a pitiful use of my time. I definitely plan working either as an intern or a research assistant at a successful organization. It seems like the general consensus is that taking time off is okay, and potentially beneficial, assuming you actually do something in that gap.