Henry
Autoexreginated
Around 20, but I think you probably wouldn't hit them all since it's a bit sandbox-y.
@malraux:
I can understand wanting to make progress after a year of play. In the Classic campaign that I play in, it took us around a year to hit 6th level... I understand that's a little slow for today's tastes. But my brain breaks at the notion that you could go through the entire Heroic tier in less than 1 year. I mean... what a waste of potential!
While it is a waste of potential if you're talking about long-running campaigns, I have a feeling, anecdotally borne out by me, that most groups over the past twenty years or so do not continue in one steady state for years at a time, and many campaigns fail or end within a years' time due to changing rosters, DMs losing interest in running the same campaign the whole time, people having children, getting married and moving out of state, etc.
In my younger days, I never had an AD&D game last more than a year; by then, someone else was itching to run their own campaign, or people were moving away, etc. Same thing in 2E, same thing in 3E and 3.5. Most recently (past five years or so), our group actually switched gears to run and finish a campaign arc over the course of a set number of levels (usually 6 to 10 levels' worth at a stretch). This gave us the advantages of not needing to swap out players who did or did not know the current story, and it gave us the sense of accomplishing something, if the game didn't just "drift off", but actually had a defined end-goal.
Now, we run a game over 10 or 20 sessions, over about ten levels, meaning we level every one to two adventures. That's still about three to five months of play, depending on if we're alternating DMs/campaigns or not, where it stretches to nine or ten months from start to finish. Lots of groups have a very fluid makeup, and it shows when WotC tries to design play with them in mind.