Again...to the best of my knowledge...Jordan never advocated the belt buckle as an aiming point. That was just where his revolver happened to be pointing during a one-hand fast draw at close range.
If we look at the pictures of Jelly Bryce's "FBI Crouch" that was prevalent during the day, we can point out that not only would the Jelly Bean not likely win any action matches with it, he'd probably be laughed off the range in this day and age.
But the fact still stands that by his own admission, he killed 19 men in his career...all of whom were armed and trying to kill him, and most of them drew first.
Modern grand masters who execute a .6 draw/fire/hit sequence are impressive, but facing Bryce, they'd spend the last 2/10ths of a second bleeding. Against Jordan or Cantrell, they'd never clear the leather.
Jordan's draw and hit has been timed at 27/100ths of a second from signal to shot...including reaction time. He once said of Ed Cantrell: "I reckon Ed's a mite bit faster than me."