Completing The Garrison Campaign takes way too long. There are 12 parts to the garrison campaign and there is a weekly lockout for each of them. This means it takes TWELVE WEEKS to play through the garrison campaign. Understandably this makes sense, as back when the expansion was first released it made for a smooth questing experience, which meant you couldn’t complete the entire thing in the first week of the expansion.
But as someone who enjoys going back to play old content and obtaining old achievement’s, this is really frustrating as I’ve pretty much finished everything in the Draenor expansion, but still have eight more weeks before I can complete the achievement “The Garrison Campaign” due to the weekly lockouts. The Tanaan Campaign also suffers from the same problem as each of the parts required are on a lockout as well.
Short version: Garrison Campaign takes too long as its on a weekly lockout, consisting of 12 parts.