I Wasn't Counting

Some campaigns that went far longer than 7-sessions that I can remember.

Carl's Champions world and my character Prowler.

Carl's AD&D dungeon world where we could play ourselves.  Thag the Evil Magic User was a force to be reckoned with there.

He rebooted that world for GURPS and it ran all summer.  One of the players sleeping with his wife killed that one dead...

He ran a more conventional fantasy world with GURPS we played for a couple of years.  My GM'ing schedule caused me to drop out.

Standing Bear ran many fantasy worlds that lasted for years and years.  From his homebrew version of D&D through GURPS.

FuzzyGeff ran an excellent nexus campaign that definitely ran longer than 7 sessions.

My first Traveller campaign ran twice a week for 9 months.  With just "The Traveller Book" and no modules no less.

Before I left for the Army, my Twilight: 2000 game ran for two years.

My semi-comical pirates campaign ran longer than 7 sessions.  It even had people watching us do the roleplaying part.  That one fell apart when two players abruptly decided they needed to leave and rather than take ten minutes to get their characters back to the ship, chose to let another player run their characters.  That player chose to sacrifice their characters to a tribal god to make peace with an island of savages.  Somehow that was MY fault.  Sigh.

T2K runs well with GURPS.  But I remember Kalisz more times than Krakow, so the campaigns must have been short.

Traveller and GURPS got some excellent runs.

Modred ran a good long time.  Alternate history where the Nazis murdering Jews opens a rift that lets magic and demons into the world.  Letting the players play characters who were both from the world and from other worlds really helped let them make characters they wanted.

But there's a scrap yard of worlds that only made it a session or two.  Players leave and don't come back after establishing themselves as essential to the campaign at a point where you can't work around it being an all to common occurrence.

K'Tanga was one such.  A gateway to another world from Zaire was the hook.  I let the players decide who was going to assume what roles and the person who took the "chosen one" job quit after two sessions and did it in the middle of the game by not coming back from dinner.