Canon EOS-5DII used to be my work camera, and often the center AF spot was the only one that worked reliably. Shooting full open did mean that I had to lean back a bit after reframing to take the focal plane shift in account. It works, basic descriptive geometry in action... With better cameras, or at least better AF systems (Nikon D4 now) it is possible to use more AF points even in low light situations. If not using largest apertures at close range it is even possible to let the camera use a cluster of AF spots for "semi-auto" focus. With D4 I have sometimes started to use continuous autofocus with 9 or 21 focus spots, as it is easy to move the cluster with the joystick. Not for extreme shallow DOF but "normal" shooting. "Full auto" I do not like. Cameras are getting better, but matte screen without any focusing aides with MF was actually most representative of the final picture, kind of miss that Canon F1 over 30 years ago...