It seems that understanding the theory behind spawning systems is difficult for a lot of players, so this post is intended to help with that. I believe that with this theory, it is possible to get spawning decisions that are quite optimal. The focus here is solely on eco spawning. Other types of spawning can be fit in with whatever priority seems appropriate and the eco spawning can scale down appropriately, still using the theory outlined in this post to make the most of the available spawn time.