If people are actually mature ans orderly it wont take that long really.

Oh you people and your silly fantasies.
For some reference, even on perfect days when everybody showed up on time, we still started 10-15 minutes late for one reason or another. I think we only had a few matches start 1-2 minutes late, and those were like the HTBA v GG v PHS matches. The all-star tourney I don't think we had even close to a perfect start time.
I'm not sure what the standard is now, but we used to do 10 min games (no OT) with a 5 minute break between each game. So for example in the February Tourney, we would play 3 maps which took about 50+ minutes total for every match. If you want to do 6 maps, that's 2 hours you have to find in 12+ people's schedules where they can all sit down and play gg2. I don't think its possible.
If you're worried about starting late between maps, you can try what I did which was a forfeited game for every 5 minutes delayed.
Edit: Btw shouldn't someone lock the summer tourney thread before next summer?