I always shebang ksh. You sound like one of those awkward nerds who embraces this crap because everyone beat up on you in high school, so now you have this overly complicated usless thing that is all your own and you can LORD your false intellectual superiority over other people now.
O/S should be about getting stuff done, not about getting revenge for when you were kicked on the playground when you were ten. The O/S should take care of all of this. That is what "O/S" means. "O/S" means "relax buddy, I'll take care of the stupid crap so you can do what needs to be doing."
It does not mean "Root around the overly long and complectaed man files and if you can't find it 'Ha! Ha!' you probably kicked my master when he was ten." Which, I never did.
Btw, just because something is invoked as "ksh" don't mean it came from David Korn. And there are several versions even of that.
Try bash.