Having to hunt down a Fel Rift and then you have 10-20 minutes of time to do other stuff, you can’t log out so you can’t progress another character and you can’t travel much anywhere in that time window.
I would rather the imp takes bit longer on their trip and you can log out and have it still progress the timer. Right now it just encourages you to either AFK while the imp is doing it’s trip, farm in the nearby area if you have the professions or just straight up ignore that it exists and do other stuff.
I think the idea of the imp and rifts isn’t that bad, but it could be much better in useability.