yes the demand is huge, it is much more successful format,
but i see your point, some players only play on weekends, they must have 7 day timeout regardless of timebank,
such tournaments need to be only a single round because some games will last a very very long time.
How far away are you from letting people sponsor tournaments? Is that a future option? Maybe you'd need a gold member subscription.
One live site I play at has a few select people who can start and run tournaments - I think they "sponsor" the tournaments. I think they are long-term members who have been giving special priveleges due to their good character loyalty to the site. I don't know if running tournaments is time consuming, or if letting someone else run them is even feasible. And I'm not volunteering! But I know there are many players here that have the respect of many members - and it might be fun it see what they would do.
I would also like very much 7 day t/o tournaments. While I may move faster in practice, getting a lot of 3 day t/o games at once causes me some problems so now and then. Although with the timebank things are less urgent and I am able to manage it.
I'm also waiting to join 7 day t/o tournaments .... they have the time out period I like best. You can study chapters in a chessbook that deal with say the Isolated Queen Pawn, if you got such a position on the board in one of your games. To study game related subjects (endgames!) is one of the reasons why I play correspondence chess, that's part of the fun ..... but I'm still waiting .......