Background:
I'm new to tabletop role-playing games, with D&D Next being my first. I like the idea of tabletop role-playing and thought I'd give it a try. The group on average meets about 3 times a month for 7 hours each session, and has been running for 7 months now.
Based on the plot of the story it's a fairly safe prediction that we are less than a quarter of the way through the story so far. It's starting to seem like a pretty significant amount of time invested already with no end in sight. Is this typical for tabletop role-playing games?
This is my first tabletop experience but I guess I was expecting for an adventure to take about a year to complete.
Edit: As mentioned in an answer below my reference to story arc could/should be expanded. To put it in context, if this were a series of novels culminating in climaxes, the overall story would likely be a series of 7 books. Each of the arcs would involve a separate territory ending in a 'final boss'. In the original question I was referencing the overall story, ie the full series, as opposed to one individual arc.
Best Answer
It varies wildly. There are a lot of factors that go into it.
How big is the adventure?
I've been in games where an entire story went from level 1 nobody to level 20 world saving hero in about 40 sessions of 4 hours each, played weekly. I'm currently running a game that's going to take two years, with 3.5 hour sessions weekly (we're over a year into it, and that time estimate is doing well).
Before that I was in a game that was following a set of published adventures. That game was going before I started, and will be going after I finish. It also meets weekly, but they have more side quests and other things going on.
There's no real guideline for how long a storyline should be, except that you want something your players can finish. If you only have until the end of the semester before people go back to university or something like that, you can't run a 3000 page adventure.
How fast are the players?
Some groups operate quickly. Everyone knows what to do and they'll keep combat moving at a high speed. They may also be focused on the current goal and ignore other things (or they may not).
Other groups won't. Sometimes you get newbies who need more time to figure out how to react. Sometimes you get people interested in exploring the world and they'll go off on side quests, or random tangents not related to anything because they want to see what's around the corner.
And sometimes, you get groups that for one reason or another wind up doing a lot of out of character talking during games. That also slows things down, as the game isn't progressing while people are telling jokes or catching up. And you know what? If everyone is having fun doing that, great! I suspect you might be having this happen somewhat, as 7 hours is a really long time to stay in character for without breaks. There's nothing wrong with that, but a lot of it just means things will take longer.
How descriptive is the DM?
Some DMs will be description light, and that makes things go faster than DMs that are description heavy. For players that want a fast paced game, being light on description can be really helpful to keep things moving.
I had a DM once who was very detail oriented. One session we made offhand comments about solving our money problems by robbing a bank. Next week, he came to us with a detailed overview of how the banking system operated and the bank security, should we want to do that. He spent 45 minutes going over that with us, based on an offhand comment. It brought the game to a dead stop, and it was awesome.
How much combat is there?
Combat can be slow, given the setup involved, and the actual dice rolling and such. If you have a lot of combat, you'll take longer to accomplish goals than if you have less. Random encounters can be a big one here.
I found that random encounters as people wandered around a dungeon were slowing them down too much from reaching the scripted encounters in the various rooms, so I just removed 90% of the random encounter rolls from the dungeon I'm doing. That let the players move around the dungeon more quickly, and made them happy.
In general, most of this comes down to time efficiency. There's lots of ways to get more or less done in the same time at the table. Beyond those, it's really about the scope of the storyline and the play style of the people at the table. There's no real hard numbers or guidelines for it, but in my experience yours is on the longer side.
Some Numbers
From my own time as a player and DM, here's some numbers I've seen:
Those numbers won't hold true for other groups, but they give you an indication of just how wildly things can vary.