Since the end result is the same as a pre-flash, and the pre-flash procedure is easier/more intuitive, I can't really envision a situation wherein one would post-flash...
Hi, I'm just the opposite - I think post-flash is more intuitive. The way I do it is to first make a print (actually, test strips). When I get to where I'm happy, except for lacking a bit of highlight detail, I'll often try flashing. Typically I'll make another test strip, doing several flash exposure on it. I use a piece of cardboard over the print, same as I would for a print-exposure test, moving it in steps. So one test print might also get flashing tests of 1, 2, and 4 seconds. If the highlights are doing what I want, I can select a flash exposure or test further.