There is another time calculation we can do that is equally important as the previous one.
I put up that surgeon's report about Oswald, and I read it several times. It says that they started working on Oswald at 11:42, and it began with administering him anesthesia. Apparently, that was done before they gave him the massive blood transfusions and fluid replacement. It doesn't appear that they did anything to him prior to that. And I assume that they used as much haste getting him to the OR as they did with Kennedy.
So, let's work backwards from 11:42. If the doctors started working on him at 11:42, what time did the ambulance arrive at Parkland? I presume it was no more than several minutes. In JFK's case, it was probably no more than one minute. But, let's say two minutes. That's two minutes from the time that Oswald's stretcher was being extracted from the ambulance. So that's 11:40.
Now, what time did the ambulance leave the PD? We can go by Bill Lord's statement that it was 11:24 when they were wheeling Oswald's stretcher out from the jail office. Remember, it wasn't far to go. There was a little delay waiting for the Brinks truck to be moved out of the ramp. So, let's say 11:26 when they turned onto Commerce.
Now how long does it take to get to Parkland? The shortest driving distance is 3.4 miles. But that was if they did what they should have done and turned right on Commerce for a few feet and then right again on Harwood, and then it was a straight shot north to Parkland Hospital. But, they didn't do that; they turned left on Commerce. And I have to believe the cops told Hardin to go that way. It made more sense to turn right, and remember that traffic was already stopped. It's not as though there was any physical danger or impracticality to do so. And there really is no excuse that they didn't, considering the state that Oswald was (presumably) in.
Hardin specified the route they took in his testimony:
"We went east on Commerce to the expressway, and north on the expressway to Elm and then west on Elm to Harwood and north on Harwood to Harry Hines, and north on Hines to Parkland."
Note that they were already on Harwood. The Old City Hall even has a Harwood address: 106 S. Harwood. I know Commerce was a one-way street, but this was an ambulance; it was an emergency; and there were two police detectives in the vehicle. So again, there was no excuse for not doing it.
There are time estimates for making that drive, but I assume that traffic is much heavier today than it was in 1963. Doing it the right way, the driving distance was 3.4 miles. That extra loop they did going on the Expressway to take it for two blocks (from Commerce to Elm, and there was only one street in-between: Main) wasted time. But, driving that route, how long would it take a speeding ambulance to get to Parkland?
Let's say that their driving distance was 5 miles. Let's say the ambulance could average 45 miles per hour. That would mean that it would take 1/9 of an hour to get there, which is 6.6666 minutes. Let's round to 7 minutes. They left at 11:26, so you add 7 to that, and it's 11:33. Then, we allowed 2 minutes to deliver Oswald to doctors, so that's 11:35.
Since the doctors started their ministrations by anesthetizing Oswald at 11:42, that's a 7 minute difference. In a case like that, a dire emergency, I would expect doctors to get started in a lot less than 7 minutes. To my mind, that leaves several minutes in which a stop could have been made by the ambulance.
Of course, that would mean that Hardin essentially lied to the Warren Commission. But if so, he had plenty of company. Recall how Fritz told the WC that Oswald said he was eating lunch with other employees during the shooting, which was a bold-faced lie. The amount of lying by witnesses that Amy Joyce has found already could fill a book.
And I believe it was Amy who found out that both Michael Hardin and his assistant Harold Wayne Wolfe died young; Hardin of a heart attack and Wolfe by suicide. Hmm. I am reminded of the saying: Dead men tell no tales.