Actually, Epcot has had extra evening hours on Fridays for a very long time. I got out my hard copies to make sure. I know they used to change the emh's in late May each year. But, it was posted way ahead of time. I would always keep an eye on that starting at three months out. MK has had early hours on Thursdays and evening hours on Sundays for as long as I can remember. Of course the evening hours were for three hours, instead of two, as they are now.
I really believe, as others on here, that those late extra hours are on their way out. That is the only reason, at this point, that we stay onsite. If the emh's go, then we'll be staying at a larger, nicer place offsite. We may occasionally stay onsite just because we like the atmosphere.