No, it isn't. Your point is that statistics based on buying at a top are not much more than trivia items, and I agree.
But since people do write articles and make talking points based on "how long it took the stock market to recover" it's worth asking what the right answer is. The result of that exploration for me has been simply to underline how arbitrary it all is, without a Guinness records team to make a final judgement.
The most serious issue is that I constantly see advice that is predicated on things like "the average length of a bear market." If you are seriously planning "a cash bucket to ride out a bear market," it really matters whether the longest bear market was 7 years or 15. And the average is affected by whether you are averaging in two sevens or one fifteen.
No, he wouldn't have, because people didn't invest that way in those days.A real Boglehead would have been beavering away for decades to build an adequate nest egg. He would have used realistic projections for stock market growth...
I would say that the idea of saving for retirement using stocks, and systematic withdrawals, did not begin until around the 1950s. You could date it as dating from the formation of CREF (in TIAA-CREF) in 1952. Before that, it was taken for granted by pension managers that pensions must be invested entirely in bonds (indeed, it might not have been legal to do otherwise; not sure when that changed).
The idea of stocks as prudent long-term investments had been bruited about. Edgar Lawrence Smith published Common Stocks as Long-term Investments in 1924. John Jakob Raskob presented something like a modern understanding in 1929 in a magazine article, "Everybody Ought to be Rich:" make regular purchases $15 a month in "good common stocks" and you will be financially independent in twenty years. He said. The numbers don't work unless you assume that you can pick "good common stocks" that are twice as good as the market average.
But Raskob might not even have known that, because what might be called "long-term stock statistics as we know them" didn't exist until the 1937 publication of Common-Stock Indexes, 1871-1937 by the Cowles Commission. And even that was just year-by-year data. Long-term averages weren't really well-known until Merrill Lynch sponsored the creation of the Center for Research in Securities Prices, in order to get data to back an ad they wanted to run. The data analysis was published in 1964.
But even more important than that is a reading of Benjamin Roth's The Great Depression: A Diary. During the Depression, Roth, a young lawyer, was constantly lamenting the fact that he just didn't have the money to snap up the bargains in stocks and real estate that he saw all around them.
Paper studies of how well you'd have done if you'd "just" carried out Raskob's plan of investing $15 every month (equivalent to $225/month in 2019 dollars) ignore the fact that even a young lawyer--let alone a salaried worker--had little chance of being able to do it.
So your theoretical 1929 Boglehead didn't have those "realistic projections" for stock market growth (Raskob's were double what was realistic), and couldn't have been "beavering away" saving because times were tough--even for what Roth calls "professional men"--and job income was insecure.