I've found the following:

Economy is usually a free-for-all. Someone may let you out. Others times, you just sit there and watch 200 people go past you. If I'm on the aisle, I'll always offer anyone inside the opportunity to get up if they want.

Business/First: Generally these exit row by row. Never had a time where the people behind didn't wait for the rows in front to exit first even on US airlines.