In the '30s, Hart opposed USN building fleet subs (around 1500 tons surfaced), saying they're too big, & favored something more like the WW1-era U.S. S-boat or Type VII (both around 1000 tons). Some of that, doubtless, was because of treaty tonnage limits (IIRC, a 52,700 ton cap).
WI Hart's proposal had been accepted? IMO, this would have prevented operations off Japan from either Pearl Harbor or Midway for most of the war.
Even if they were capable of reaching Japan (& I'm dubious), the on-station time couldn't have been more than about a week, which makes it pretty absurd (given a 10 day or two week transit each way

).
There are proposals for how smaller boats could have been used. I'm of the view SWPA operations were too unproductive & dangerous to make that the standard.
If Hart's approach had been followed, what would have resulted? Would Japan have lasted longer?
Any other thoughts?