From another recent thread
Quote Originally Posted by Rongway View Post
It does prioritize duties in progress. However, you won't be offered the spot if the group is not looking for members yet, or if someone else has the in-progress offer waiting. You could queue up immediately after your friend's group kicks someone, but as soon as it goes to looking for members, if there's already someone in queue with in-progress checked then they have 45 seconds to accept. If another duty pops during those 45 seconds, you get that one instead because your friend's in-progress group has already "found" someone--even if he hasn't accepted and entered yet.

As for how often people queue in progress, you're underestimating it by a long shot. Many people queue in progress without having been requested by friends, which would contribute to you not getting your friend's in-progress duty even though you queued when asked.

To allow people to queue only for duties in progress would be heavily abused for quick clears where people only want the last boss kill, far more abuse than the additional benefit over the current system (that is to say, the current system already finds replacements as soon as they are available, and the flaw that you are seeing is simply a side effect of the second-in-line situation described above, which is not a prioritization problem but a slow human response problem that won't be fixed by allowing only-in-progress queues).