The SBT aside, there's no getting around the "time spacing" between the 3 shots. The quickness cited by ear witnesses between the 2nd and 3rd shots rules out the bolt action Carcano being responsible for both of those shots.
You are conflating issues. The claim being addressed was that there were many shots. More than three. The witness testimony is compelling that there was a maximum of three shots. If you add in those who heard only two, that's almost every witness to the event. Very compelling that there was a maximum of three shots. And, of course, that matches the number of recovered shell casings from Oswald's rifle. To suggest that bullets were flying everywhere in DP is false.
In terms of what you are suggesting, many witnesses did claim the shots were not equally spaced out in time. They didn't have a stopwatch timing the shots, however. So any conclusion that a shorter time span between the 2nd and 3rd shots precludes Oswald from firing those shots can't be drawn from the evidence.
