I apologize if I came of claiming your wrong, not my intention, it just seemed like 10 feet is too much, I'm not good with calculations and this is how I was thought from a young age.
Now here is why I say this, I've shot several deer at around 300 yards, if it is further than than that I am more likely to not take the shot but it depends. On these shots I've taken I aimed about a foot in front if it's nose and all shots were right on the boiler room.
The javelina I shot last season was a little over a 100 yds away going full speed from left to right and with my 7mm Rem Mag and a 140gr Ballistic Silvertip at around 3,250 fps I aimed at the center of its head and hit it right under the ear, thats about 5 inches from aiming and firing point. Now I dont have a mathematical explanation for it but it works
I've done Silhouette Shooting competition, smallbore and high power for over 30 years and this is done off hand, no prone or kneeling to shooting like this. I've shot one deer while kneeling and not a single animal from prone position, haven't even tried it, and up until a few months ago I've been thinking about trying it.
I'm not saying your math is wrong, just that my method works for me. Now, the shots I take are the ones I can make, not some hail mary shots hoping to get lucky. If you have taken any like these when you pull the trigger you know that animal is going down.
Now I shoot several thousands of rounds between .22 LR, 223, 7mm-08 and my 7 Mag per year, all done of hand, this is to make sure that when I pull that trogger my quarry is dispatched fast and humanely.