As I'm finding myself spending more time in Neverwinter again, I have to acknowledge that the game is really good at making itself feel "more-ish". There are lots of little tasks that literally only take a couple of minutes but are very rewarding - to prevent this from being exploited they are usually limited to once a day or once a week per character, but to a casual player that's not a problem.
So I end up doing one thing, knowing it will only take five minutes, but then I think: "Oh, I might as well do this other thing that also takes only five minutes" and more time goes by. Eventually I go: "Oh, I might as well do all that stuff on my alt too while I'm at it" and there goes my afternoon.
I think this is one reason I've had such an on-and-off relationship with the game in the past, because it's easy to get sucked in and play a lot, but in the same vein it's quite easy to burn yourself out, at which point I usually need a break to recharge my batteries.