Keldryn
Adventurer
Never understood why the DMG cones out later.....we want to run a game, not read the PHB for months.
Perhaps to give them a little extra time to put that final polish on the books. They'll do a better job catching errors if they're not trying to get three books ready for simultaneous release.
The AD&D 2e core books were staggered by a few months as well. And let's not even get into AD&D 1e, with the MM released in 1977, the PHB in 1978, and the DMG in 1979...