I thought once I hit T3 I'd need uncommon duty officers.
Used to be that was the case but around Season 7 (possibly at launch) they transitioned over to all whites because people were starting to get there and were very displeased, but the big motivator, if I recall correctly, was that people had managed to push pretty far along the new Romulan Reputation system on Tribble and were not pleased at needing to burn hard earned blue and purple quality DOFFs on the fighters and the Devs had a lightbulb moment and made the changes to the Fleet System at the same time as they did the Reputation System.
Originally Posted by bazag
There might be an occasional Green, blue or purple Doff for specific projects but generally all DOFFs are common.
Can you name some of them? As far as I'm aware all the projects calling for DOFFs now only take whites.