I have seen some good dogs run for an hour, even two hours, or all day hunting. However, I was fortunate that David Surber let me run Logan Elm Blue Skim for about a month and my brother ran him for about 4.
He just didn't make many mistakes while trailing a rabbit. He embarassed a couple of my 2 year olds in semi tough conditions more than once. He could claim a line nicely, run the track with good speed, and had good seach ability