It depends what you are doing. If you are expecting trouble, chamber a round and let the hammer ease home, but be careful.
I ride all day horseback and almost never find trouble. Given the potential of having a fall or snagging on a tree or fence, it is better to have an empty chamber. Riding in a car or truck (on private property) sure, maybe one in the chamber. Riding an ATV or something less secure, no.
He is right though, it is how you train that matters. As a former Marine, I have spent a lot of time with weapons. Again, the situation dictates round chambered or not.
When can you afford not to expect trouble? Varying your ready status can lead to missteps when your adrenaline is raging.
Well...as long as trouble isn't looking for you. I chose a carry solution that was secure to carry ready-to-go, fully concealed, and tamper-resistant, and verified I can draw and fire in a fraction (1/5 to 3/5) of a second without a glitch.
Of course I only carry when I'm in a free state, California DOJ minders, so don't get all cross-eyed on me and send the SWAT next time I saunter on down to Whole Foods.