This very subject was addressed in the Dec. issue of Shooting Illustrated, page 52, written by John "Shrek" McPhee, a long time shooting instructor, etc., etc. He basically says that "trigger jerk" is a myth according to the "thousands of videos" he's watched of his students, from brand new students to Special Ops forces. In his article he states the pie-chart diagnostic tool is based largely on outdated ideas. There are more words than pictures in the article so I didn't read it like I was studying for a test, but I did do the quick speed-read. Basically he said a good, strong, solid grip is more important no matter how "badly" you pull the trigger. I won't argue with him or anyone else, but it's what he does. I suppose if you can get ahold of the article it may help you. Shooting Illustrated is one of the NRA magazines the members get so if you're a member you may have access to the article online. Good luck, and Merry Christmas!
Peace! Jeff T.