I don't really understand why text editors seem to do this, but it's inconsistent with how the rest of the operating system and browsers work. Ctrl+Tab and Ctrl+Shift+Tab usually move either forward or back 1 tab. I'm not 100% on the logic of how Sublime Text 2 and Notepad++ (possibly other programs, as well) behave with this function, but it just seems to jump all over the place. It'd prefer it if Sublime Text 2 would change the default functionality to match other programs.
Tip: I use the two thumb buttons on my mouse to move forward (Ctrl+Tab) and backward (Ctrl+Shift+Tab) and it is a very time saving method of binding your mouse keys, especially in browsers where you constantly open new tabs with middle-click.