The OP was only hypothetical practice, but something rather useful I believe. I can recall a couple of times personally when the sticks have been abandoned after cycling quickly for a follow-up and the animal has run 30-40yds or so before going down.
There really is no issue with folk practicing for this eventuality and I cannot understand some of the negativity - no-one's advocating 200yd offhand headshots, for goodness sake.
Anyway, the sun's out and my youngest has an inset day, so we're going to take the air rifles and walk up some hedgerows on our fields - lets see if he can bag a nice rabbit for the dog with his HW57 over open sights.