90% generally, don't show.
I ran across a situation a few days ago where I think I would have benefitted from actually a lot of showing.
Online, HU against a UB pro. He ended up beating me, no surprise there, with 74o which he had aggressively raised PF. I hit top pair (AT)and he slowplayed the flopped 2 pair.
I got to thinking that had I shown him some of the junk I had taken his money with, he might not have been so agressive. It might have worked out he would think he had to be even more agressive, but we'll never know that. His agression talents are way bigger than mine.
Very specific situation where I know my opponent is paying attention.
That is the only time I can remember ever entertaining the possible strategic value of showing.