What's the point of this ? 10 days between each city is not that long, and I don't think the main problem of new players who can't catch up is not because of the timer, but rather because they can't afford new cities (you have persons stuck with the same city count for years ...). I'm not against this suggestion, I just don't understand how this would help reduce the gap between low & high tier.
Also, I find it logical that people who have been playing this game for 5-6 years now have a city advantage. This would be ridiculous if older players played 5 years straight to get catched up quickly by a new player.