Works on my plane (a Husky with Constant Speed prop). The idea is that
at 10,000' you can lean all you want and it won't hurt anything, at
full power for that altitude. Now, you will be rich of peak, just a
little rich at 8000' full power, and so on down to Sealevel where you
will be 150 or so rich of peak. Works great. You are leaned enough to
be rich of peak and you don't even have to go to peak, at Sealevel
(which can cause detonation), to find out where peak is. You will be
leaned enough rich of peak to be safe, but not so rich as to waste fuel.