What ever works for the photographer... is definitely the way to go. I think I use only a very small per cent of the available settings. With the 5DIII there are something like 61 focus points and you have six ways to configure the autofocus ; )
The neat trick about using AF-ON / half-press disabled is that you pick your focus target and recompose (keeping the distance fixed). The 5DIII allows you to set one specific focus point --or-- a group of focus points, or use all 61 points...
The 17-40 is a good range... if I am traveling with one lens, many times it's a 35mm... but I also like the 28mm / 50mm combination.
Funny that the photo was taken in WI... after his retirement, my dad raised sheep south of La Crosse, WI
Scanned from prints that were made in c. 1977...
Casey