I had actually some problem with taiwan players. 
Sleeping hours were an issue in that case.
I tried to replicate the timesettings in a slightly slower pace: 1 day main time, followed by 1 day per 5 stones.
Since I often check my phone for pending moves, it means for my opponent 3 to 5 moves per day.
Six challenges accepted:
- 2 annuled because opponent didn’t play a move
- 1 TO after 8 moves
- 3 TO after 72, 112 and 158 moves respectively
Sadly, people doesn’t pay much attention to timesettings when accepting a challenge.
I think now that building a good friends-list is a better way to have fast correspondence games.
Creating small tournaments could be a way to do so.