I think the problem here is although there are some basic mph/mils formulas, they really won't help you much in real life. It comes down to experience(practice) which develops better reaction and instinct when hitting moving targets. Yes, mph/mils will help if you are at a range where the targets are moving at a steady speed, perpendicular to you, but in real life it is completely unpredictable what your target will do, and consistency in movement is almost never the case. I get what you're asking, and that it is possibly more of a hypothetical, but most of hunting is setting up a good shot, which suggests the target should not only be stationary, but presented at an angle where you can take an ethical shot. If the aforementioned situation does not happen, more times than not you need to be willing to just let it go. A lot of us that have practiced shooting movers have done so not for hunting, but for shooting at moving humans, where a clean shot is not completely necessary like it is hunting game animals. Hope that makes sense. I don't believe you'll get a good/complete answer to what you are asking here.