The "Previous" button has a rewind icon, and as such I expect it to take me back to the most recent activity boundary. I use FlexTime exclusively for a Merlin Mann 10+2 routine, and my main interaction with FlexTime is when I return to my computer and want to restart the 10-minute work session.
If that's not what the "Previous" button is supposed to do, please tell me about (or add) a button that does work that way.
I'm also not sure why "Reset" (with the rewind-to-beginning icon) *stops* the routine. Why not just rewind to the beginning and have a separate stop button? Or relabel/change the icon for "Reset" to be more accurate?