Yes. When I decide to go for a test, I schedule it. Nothing like having the cash already spent to give me incentive.
Tests for similar subjects I will schedule closer together (how much difference is there between Win2K OS systems?). Always group similar tests together. I took my SQL Server tests within two weeks of each other. I was confident I knew the material and I could not see the point of waiting. When it came time to take the OS exam I gave myself another month, but then scheduled the OS exams together (I was taking the MCDBA and MCSE tests together).
Quand on parle du loup, on en voit la queue