First, are you allowed one instance every 12 minutes (60/5), five per 60 minute period, or maybe even five per "clock hour" (5:00pm - 6:00pm)?
Second, sometimes I'll leave for repairs or to empty trash from inventory and then it won't let that same toon back into the same instance. Is this a bug or does anyone know a workaround?
Not complaining- just want to understand the mechanics.
Five per hour, the timer starts the moment you enter the first instance.
As for not being able to re-enter an instance that you were in before, that's not working as intended, but has been that way for a very long time.
Everytime you enter the instance portal 1/5/h gets used up. Hence going in and out 5x times locks you for 1h even if you did not even kill a single mob.