It looks to me like the only available time controls are 1 move per x days. It would be nice if we could set it up for y moves per x days. So instead of 1 move in 3 days, you could have 4 moves in 10 days. If you haven't made 4 moves in the last 10 days, your time is up.
I like your idea, but lets say I play white and you play black. And using your example we each make 3 moves in less than 10 days, but I wait until 9 days 23 minutes and 59 seconds before making my fourth move. You would have to be keeping a close eye on me so that your fourth move did not exceed the time spent between my first move and your first move. For example (worse case), if you made your first move 1 second after my first move you most probably could not repeat that feat on your move 4 and you would lose on time.
Each player's clock would be independent. I would have 10 days for my 4 moves, you would have 10 days for your 4 moves. My 10 days don't count down when it's your move.
It looks to me like the only available time controls are 1 move per x days. It would be nice if we could set it up for y moves per x days. So instead of 1 move in 3 days, you could have 4 moves in 10 days. If you haven't made 4 moves in the last 10 days, your time is up.