Re: flight hours: Boeing had stated they were flight testing updated software prior to the second crash, had they not? So maybe they are counting some of that time?
Not saying they should; on the contrary, they don't get to start counting final fix flight test hours until they have a final fix, with no further revisions, approved by all global authorities. That final rev? Yeah, count those hours.
More relevant would be the number of times they pushed into the corners in question, with minimum acceptance trained pilots at the controls, and got MCAS to activate, plus actual failure modes activated in flight, with the same experience level pilots. Do that x# of times, simulating 20 years worth of the global fleet experiencing those corners/failures, and I'll even accept more experienced pilots for the later tests, approximating the maturation of the global experience levels.
So what we talking about, fleet wise? Several hundred envelope corner excursions, and thousands of single AoA vane failures? Plus a couple dozen 2x vane failures, plus all the added related equipment/computer failures? More? Less? By orders of magnitude?
Whatever it is, add it up. Fly them all, with at least nominal surprise (OK, test pilots will know something will happen in testing, just not what and when). You're asking us to fly it all over time; OK, you first, Boeing.