User blog comment:Zedmaster3000/ Sectoid (XCOM UFO DEFENSE) vs Sectoid (XCOM ENEMY UNKNOWN)/@comment-8384215-20130430204353/@comment-143604-20130430223319

Pages only get removed if there's no planned battle for the warrior, not if there isn't one completed. You could have a battle sitting on your reservation list for years before touching it, and the warriors used in it would still qualify for a page.