I have never seen anything on Mark Sullivans films that suggests that he or any of his clients have ever deliberately gut shot any animal.
Perhaps some people are confusing a gut shot with the quartering away shot using solid bullets where the shot will enter the paunch and then continue to travel forward into the vital chest area.

Nor have I ever seen any time where he has taken anywhere near TEN minutes to finish an animal off that could have been killed sooner.
Maybe I have a different "Shot to Death" than others as in my copy the final shot is delivered in well under 2 minutes.