So basically my suggestion is instead of when 1 guild clears the current progression, two months later the next is out. But to make it when 5 or some number of guilds clear it instead. Say 3 from each faction clear it. These are 10 year old fights and it's not hard for it to be cleared why rush through the content?
http://nsa33.casimages.com/img/2014/10/ ... 453744.jpg