Sometime I think it would be a good idea to separate Debian in three/four parts with separate release schedules. Say : Debian-base, Debian-desktop, Debian-server and Debian-developers (or something like this)
Different release schedules would allow for apps to upgrade more often, with debian-base driving the full release.
But then, I am aware of the difficulties of that. Maybe now, with Testing under gradual freezing, we well have something similar.