Needs to be a 20 min cd timer if..

[Umo]

On a side note, there's another issue with low-specs rigs and loading times where you may be stuck on black loading screen after changing zone, so you may get yourself automatically withdrawn because the timer runs out. It happens to me from time to time (although it got better lately), annoying as it may be, so imposing a penalty before entering the dungeon wouldn't be fair in those cases (aside from what jabbywocks stated).