My answer is "it depends".
I had a Browning A-Bolt Euro, with butter knife bolt handle, and used it one season. Something about it just felt clunky and clumsy to me. Even though I practiced with it, I couldn't come up with a quick and natural way to cycle the bolt. I got into a covey of does in a green field one evening and was only able to get one of 'em, because I couldn't cycle the bolt quickly enough, whereas, had I had a standard bolt knob, I believe I could have gotten two of 'em (if I'd had my old #4 Mk1 Lee Enfield, I mighta gotten three of 'em). I traded it off soon afterwards.
I once borrowed a friend's Mauser traditional German sporting rifle that had the butter knife handle, double-set triggers, and Mannlicher stock with hogs-back butt and comb. The feel of the rifle was great, the bolt came to hand naturally and cycled Oh-so-slick, smooth and quick, and pointed perfectly for me. I really didn't like the way that rifle looked, but it sure operated to near perfection of efficiency, including the bolt. The way that butter knife handle was executed, I'd put it up against most any regular bolt knob for quickness and ease of operation. I was stupid at the time and didn't buy that rifle.... Live and learn....