Well I guess it depends on how far away your hands are from each other
If the joystick is only like an inch away from the buttons you're probably going to have to tilt your hand more, and to compensate, would have to angle the buttons more (by angling the buttons I mean like this, except without such a steep incline)
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It's somewhat of an inverse relationship I believe, I mean, for example (not accurate) if the button/joysticks were seperated by 1" you might want to angle it 25degrees, 3" 15 degrees, 4" 10 degrees etc.