i agree with puramu, don't like that system. its giving teams no incentive at all to play earlier than default date, because
a) its important to have a good rythm - say, playing each sunday night - when playing a tournament (in my opinion),
b) once you played earlier than default date, nobody can guarantee that the next team will agree to play earlier as well
and c) you can always force the opponent to play at default date, so you can decide about your own rythm if you choose to play then. There is no reason not to do this, if the date generally suits you.
so everything this system does is confusing/distracting players with 2 mappacks at the same time.
you can still give the teams the flexibility to move the matches; for example by having the matchweek start at thursday after maprelease, default date sunday and last possible match date the following thursday. the point is, the default date should be the logical day to play a match because most matches will be played then anyway.