1 month to develop a map that we play through in a day. The enemies never change, so if you've done it once, you've seen everything it will ever have to offer you.
1 month to develop a map that we can play hundreds of times with different results because the enemies are always different.
I don't understand the business sense in continuing to develop Klingon PvE. It will always take them ages to design, implement and test a mission that most of us will probably do somewhere between 0-5 times before we're bored with it. PvP content has so much more replayability.