Can't say I've ever seen that said or implied around here. When is a magnum necessary? Rarely, unless truly long range hunting and needing to pack a punch way out there where smaller cartridges peter out. Let the numbers tell you what you need based on the hunt. Keep it at or above 1500 ft lbs retained energy on elk for example. Use that as your baseline and then figure out what your longest shot could end up being. Throw all that in a ballistic calculator along with your bullet, velocity, verified BC, elevation, etc., etc. and see if it meets your need. If not, go bigger, faster, or keep shots closer. Great to have plenty of options though.