Charlie, I believe you are correct on the liver shot...my bad. I don't have the book in front of me.

Trout states on many questionable shots, like the neck shot that I mistakenly made a few weeks back, that getting on the deer in 20 minutes is best. He states that there is an (obviously) huge difference in the heart rate of a bedded deer vs. a standing / walking / running deer. On these questionable wounds it's better to get the heart pumping to make them bleed.

Gut / liver shots are several hour wait yes.