When I started writing my story hour, I was already a year and a half behind. Close to two years later I'm only now starting to make headway into shrinking the gap between where the game is and where the story hour is.
For me, story hour fatigue sets in because the task is just so big. The game is on-going, which means that the writing is on-going, and I know that even if I caught up with the game "present" I'd eventually fall behind again. It's the nature of the beast and something I didn't quite grasp until I was doing it.
I don't know if it's a useful perspective, but I would really love to be only a year behind. I can also say that in bits and chunks, I am getting there.
A couple things that are helpful to me, although not necessarily useful for anyone else:
1. I have a partner in crime. Fajitas, who DMs the game, also serves as fact and sanity checker on new updates. We're both writers, and it's useful to have someone who is in there slogging with me. Also, I'm not above looking at something coming up that I don't want to tangle with and saying, "Here, you write it."
2. I have a backlog. In part, this is necessary because I have to build some lead-time into the schedule because of outside notes (see point 1). But one of the nice things is I can have a couple months of no writing and still update regularly. Now, I don't particularly recommend underemployment with limited internet access as a means for catching up on story hour writing, but... I also won't deny that it works.
I will say one of the benefits to running behind the game is it does give you the freedom to write events out of order, and then fill in the gaps later. Some games need to be written up fresh; others are better with a bit of perspective.