I don't it's fair to say that the pending list should be your main source of missions. If you like to play Single Player Missions, at least a couple of missions are reviewed each month. I know that's not completely up to spec, but we have had some technical difficulties, which made reviewing impossible for some of our reviewers. These difficulties have also made some of our staff have to focus on the technical side of OFPEC, rather then reviewing missions.
But if we talk about MP missions, you are right. It has always been difficult for OFPEC to review MP missions. Reviewing an MP mission takes at least as much time getting the review organised as reviewing the actual mission.