I can speak from both sides of the fence as well, having been a player who made a character and never saw the game take off, and as a DM who has let a game or two slip for a long time.
Just as the others before me have mentioned, the lack of game updates on the DM's part is mostly accredited to me burning out and my mind being elsewhere. My players, my VERY patient players, have seen an hiatus or two in my games. But I have not given up on them, I plan on seeing the games through to the end, I at least owe that much to my players, both of us having spent considerable time into the stories that have unfolded. I will be the first to admit though, if it helps any, that I have not been following that golden rule of being consistent. Let me explain in hopes that others might be able to see this post and go 'oh yeah, that would make sense'.
When my first game came out some 2-3 years ago it seems, post activity was high, like most other games that start out. Eventually it tapered out to just a few posts a week, then two, and regrettably, one post a week at times. This posting inconsistency is something I am attributing to my having too much on one plate. I bit off more than I can chew, set up a second game on top of my first. Now this was just forum work. Outside of the forums, I also lead a face to face game with other players. As you can imagine this would drain my focus on certain games considerably. But I didn't stop there either. I was also part of many other games on this site as well. The DMs who had me as a player may have seen a drop in my posting rate as well. This posting behavior as a player, and my posting behavior as a DM, I could not help but find a correlation.
I guess what I am trying to get at is that those who run more than one game will more often than not have a hard time staying consistent, unless their DM style is inconsistent to begin with, but then that should raise some red flags if that's the case. The GMs of the Unseen Servant (
viewtopic.php?f=21&t=2417 ) is a great place to check out for all players who are looking to join a certain game or find out more about a DM running a game you are in interested in. If the DM is well known on this site, but you need some info on his play style and habits, this is the place to go to for such information. You can save yourself a lot of time and frustration this way and potentially avoid a game that might die within the next few months of its start.