1-2 cycles, faster if it’s particularly watery or you run over it in a car
For human poop, to go from your butt to being something you can plant things in takes at least 20 days, assuming you use the current best practices.
If you only want it to be broken down enough to look like soil, a few days, but don’t expect it to be safe, or to be good soil for planting.
Generally, if you do “hot composting”, the temperatures will kill off any potential pathogens quickly enough, and break down the components into a usable state in about twenty days, though there are variables that could change that slightly.
Believe it or not, this is actually a thing. The EPA even has standards for how to turn human waste into a composted soil additive. The practice of using human waste as fertilizer has been done across the world for thousands of years, with varying degrees of success and safety.
Obviously, human waste breaks down at least slightly different from other animals. Herbivores poop beaks down faster, and tends to be a little richer in the stuff plants need. Once you’re dealing with carnivore poop, the extra fats and such make it take longer (and may well exclude the poo from being good fertilizer).
You can actually buy composting toilets that aid in the process. We considered doing so when the bathroom was last in need of major work, but it wasn’t a good fit for our household.
