...
Both Avedon and Penn were, way back in the film era, usuallly cited as top photographic role models by the dozens of commercial studio photographers (food, editorial, fashion etc) I dealt or competed with (at my much lower market level..mere $400 day rate). I think Penn was admired most for distinctive "natural-looking" lighting and Penn for straight ahead simplicity..
I admire and have tried to emulate both.
Both did color work as well as B&W, usually 6X6 or 8X10,. Almost always with studio strobes. Assistants, styulists. Total control over everything but their human subjects (Penn even hauled a tent studio into jungles and deserts).
I occasionally see hints of Penn's influence in Photrio's "Media", rarely Avedon's.
What about you? Do you sometimes think about Penn or Avedon when you're making casual portraits?