Yikes.
Not that it would be "easy" as such, but I suspect that 1 hour several times a week would be easier to manage for some people than a single 4 hour block once a week.
So, if 4 hours is the standard, that means the average game takes something like 12 weeks to finish?
well 3-4h. Many players often incluede many wars... and when that happens we slow down time.
But i would say that 12weeks is possible, but more likly 15-20weeks. But it's hard to keep people dedicated for that long.