I must disagree a little, while I have thought this too. For a real life analogy, I think of it like horse racing. Let’s say you take a horse out but do not ride them in an event. Now you still have the travel and care when you get the horse back to it’s stable. The animal was just stressed a bit from the move and needs recovery time. For the game, the unused dino was fielded, ready to go, but simply not needed in that battle. It makes sense to have a general recovery time associated. Besides, it’s nice to have a preset recharge time, that can be faster with dino bucks. Compared to the alternative like maybe a 2x time penalty for a KO’d dino that was used as a meat shield for it’s high health.