Chénier: That can be solved, for example not letting a unit travel through more than one region per turn.
EDIT: No, that is a bad idea, actually that one character cannot travel more than 12 hours per turn. Things would remain the same on that matter, and there wouldn't be possible abuses from it that don't already exist.
Telrunya: I mentioned that on the linked thread. The idea is not only for people who'll never be able to log in twice a day, but for those who'll only be able to log in just once a day for some time, like in a half-active period (college tests, lots of work, holidays), instead of the current active/inactive separation. It would be a way to smooth the border between both of those.
