Our team noticed that a rejection issue (when a task is rejected and an issue is automatically added) doesn't have a planned completion date automatically set. There's currently no way to set a default duration for these types of issues. Rejection issues are always high priority to us, but in the work requests queue for the team, it doesn't appear that way because there's no due date.
I'd recommend the ability to set a default duration for Rejection Issues just like you can set default durations for issues that are submitted via request queue.
For Workfront product team's reference, this stemmed from support ticket/request #1146034.