People keep saying how the wait is long for DR DF's. The first day I found this to be true, but then I remembered to tick "Join PT in progress". Since then I've come upon some interesting situations, but more often I've been lucky enough with my BRD to end up at the second or just before the final boss of every dungeon. Sure you miss out on a small amount of mob dropped Gil. However, you help a PT finish their dungeon or get a few tomes and some Gil even if there's not enough time left and if you don't complete the dungeon with this method, it doesn't count against your daily run!
The longest I've waited with the in progress ticked is 11 minutes. You do miss out on HM Primal runs since it will usually put you into a dungeon queue, but that's not a major dealt o me anyway.
Happy hunting!