I'm a big proponent of back button focus. I've used it for many years and swear by it, pretty much never turned it off. That is until last Saturday.
I was the event photographer for a gymnastics meet (for the third year) and was using a rented 1DX. I shot with the same thing last year and can't imagine going back to the 5D III, although I certainly could. I was only shooting the floor routines with a lot of fast action and I started shooting with BBF, like I did last year. Early in the second session (2 of 8 total), I really started feeling pain in my hand from stretching my thumb to focus. Then it dawned on me: Why am I using BBF when for this event I ALWAYS want the camera to be focusing. I was constantly holding the button in. I turned of off and went back to half shutter press for focus and it was amazing how much easier it became. Just one button to think about, no stretching of the hand, fast and easy. In addition, I was nailing focus on way more shots that I had been with BBF.
The meet is over, the camera is returned, and my 5D III is still on BBF. That's how I will use it most of the time - but not for gymnastic meets. I wish I would have thought of this two years ago...