Just spent a week in Cyprus photographing birds. I was shlepping the 5dIII + 2xTC + 300/2.8 and my wife the 7DII + 100-400 II. She knows absolutely nothing about photography and just uses my setting C1-C3 and back-button focusses. The only time it went wrong when she (initials MF) saw the MF-AF switch (I am AF) and wondered why it wouldn't focus when she switched to herself. Still, she really saved the day when we found some flamingos flying and I locked down with a "card full". She took the the two of the pairs in flight and I did the massed flight and the three head on.
5D III, 7D II, EOS-M, Powershot SX50, 300/2.8 II, 1.4xTC III, 2xTC III, 70-200/4 IS, 24-105, 15-85, 100-400 II, Sigma 10-20, EOS-M 18-55, f/2 22.