Nothingness: I'd never recommend playing a game where the bonus is less than 24 hours. With ../0.6/.. it means you basically have to be online every 6 hours, on average, just to make sure your time-buffer doesn't decrease. With ../0.6/.., if you sleep 7 hours a day, and be online the other 17 hours, you still may lose the game on the clock. It all depends on when your opponent moves - which is outside of your control.

I'd never play a Fisher clock (or any other clock) with a time-to-move of less than 24 hours. (Not that I ever use the Fisher clock on BK. I'd love to use the FC, but on BK, FC implies no vacation days. And since many of my games last months, if not years (due to slow opponents, and playing games like Anti-Backgammon, or 21 point Cloning Backgammon), playing with vacation time isn't really an option for me).