Kind of a waste of time in my mind. If I'm going to go out to an event, I mean to be there for the weekend otherwise, it's just not worth it with all prep time it takes. In the case of WWI, since it only comes twice a year, there's no excuse to bug out unless you're a complete wimp or have a real emergency.
When we were actively doing WWI out here, the battles were 24 hour scenario and we didn't shut down for anything- if you couldn't deal with it, you went to the parking lot. Otherwise, it was just like the real thing (as best as we could get it). There was a lot of down time and it gave us a chance to socialize. Hell, sometimes we even did a variation on the Christmas Truce and we'd have informal gatherings in No Man's Land.
The idea was to definately socialize with one's comrades. That's one thing that put me off about WWII out here- everyone would run around the woods during the day, pop caps, and then go back to the barracks and get stiinking drunk...and then bug out the next morning. Considering it was a three-hour drive to Camp Roberts for me, it wasn't worth it for one day.