Contested areas in maps
I’m not really sure what causes them to be retaken – but I have a feeling it is possibly player numbers and proximity. I remember doing Harathi a long while back and the camps would be retaken literally 2 or 3 minutes after I had captured them.
The only benefit comes from if that particular camp has a meta or longer event chain connected to it. Apart from that there’s nothing but experience and karma to be gained from doing the events. A lot of GW2 unfortunately ends up like that. At launch when all the maps were full it wasn’t so bad because it’s really fun going around through events with a group of people – but now that everything is pretty empty events feel very superficial.
I’m pretty sure that 99% of events are timer based. They seem to range from between 10-20 mins. Of course there are some events that wont happen unless another event is done before it or it is activated via a certain npc with a quest icon above their head.
If you are just completing maps I would pretty much advise ignoring the events unless you want to test yourself, get the reward or to make it easier to do the map in question if the event is blocking that.