I have no problem butterflying pork. My issue trying to cut chicken breast into to thin slices is that the side that was attached to the bone has uneven loose bits. I may have to take a picture next time I cook chicken breast. I don't have a problem cooking them whole without them drying out.
that can create issues - I find pressing the breast down, a thump or two, usually flattens them enough the bottom cut is more uniform.