The duration of dynamic events?

GW2's Dynamic Events Content is starting to sound pretty cool.

There's something I've not seen explicitly stated yet though, and that is how long these dynamic events take to play out. Reading between the lines it sounds like there are two activities affecting timescales involved:

1. active participation resulting in a state change (success or fail mechanics)
2. nothing happening until the conditions are just right, resulting in a state change (trigger mechanics)
   

The former is equivalent to what we know questing activity being today. Kill ten rats, collect 100 ogre ears, that sort of thing. Timescale: minutes to tens of minutes.

The latter would depend on either other events cascading, or players performing some specific action like activating a McGuffin device. Timescale: days, weeks, months, possibly more.

Personally, I'd like to see some long-scale events added to the mix too. Huge community based events that stretch over hours, days, or weeks of activity by dozens or hundreds of players to finally tip the balance and effect a state change. Consider the resource gathering efforts to open the AQ gates, or the unlocking of the Isle of Quel'Danas as extreme examples.

The point being, it would be good to log on over multiple days, and see measurable progress on change being effected in the world. This, vs. not knowing what state the world will be in when you log in, just to do the equivalent of some random daily quests and log out again.

My theory is that this form of longitudinal game play would have an effect on the social dynamics of the players, strengthening and shaping the community for the better.