I don’t know about your experiences, but in my experience the AI has ALWAYS recast if the Pathfinder generated an Extra Turn (which is >90% of the time…). Chalcedony and Xenith were the worst of it, because Xenith creating more Gargoyle Gems slowly increased Chalcedony’s looping to infinity% and beyond.
Similar things happen with Detect-o-Bot, but at least that troop eventually self-destructs. Copycat and Necrocorn can loop themselves, too, but not as effectively and their loops don’t deal actual damage.
The Journey troops were, however, relatively easy to obtain and did not require ANY team synergy (beyond matching Troop Types) to set up the infinite loop.