I think it’s a matter of semantics - butterflying a chicken breast / beef cut /etc implies leaving a ‘hinge’ - often for stuffing…
but butterflied shrimp I have always done (like a hour ago! shudda pixed…) as you describe - cut thru but except leave the bit at the tail attached/uncut. don’t think I’ve ever seen the tail split but still hinged on the long side…
these are a tempura batter
these are ‘beer battered’
