Instances reset every 8-15 minutes if you aren't in it to lessen the load on the servers, I imagine.ok so my only gripe so far about the game is that town portals timeout after a while. I went afk, and came back and it had closed...
I see no reason for this to be a mechanic. At least we have Waypoints, but even then I had to walk and fight across a big zone to get to where I was...