I think I picked this up somewhere along the line.....
The long held wisdom says that with constant speed/variable pitch prop/engine combos, you 'square em off' e.g. 2400 rpm/24'' Manifold pressure in the cruise.
I was taught that bout 15 yrs ago and I believe it had been the norm for many moons. I believe Lindbergh worked out that by upping the Manifold pressure and reducing the rpm( analagous to top gear on a bike but low rpm) such as 1800rpm and 28'' Manifold, he got a significant range improvement. All the engine bods reckoned that the engines would suffer serious damage - short or long term I couldn't say but I believe that Ls concept contributed directly to the Yamamoto interception.
Hope this helps and if I have remembered incorrectly and/or am talking cobblers, I apologise unreservedly
