Yes not all types of landscapes will benefit from tilt-shift and some may actually suffer. Obvious counter-indications...shooting through some sort of portal, nearby leaves at the top of the image, people standing nearby in a field. Or just a scene where nothing is closer than about 80 feet.
But sometimes I like to exploit the texture of nearby grasses and ground textures in contrast with distant horizons, all in sharp focus. In that type of situation TS is a life-saver. For instance, On a 6 panel panorama it reduces the number of shots needed to 30 exposures (5 HDR exposures sets at each of six panel positions) from about 120 (5 HDR sets, for each 4 focus planes, at each of six panels). I may need as much as 15 minutes to really line up the lens to work ok at all the panels, but when it all comes together I just feel so alive!
For a standard of focus that is close to what large sensors and good lenses can actually deliver, depth of field simply can not contain 3 feet to infinity at any diffraction-free aperture. Those DOF marks on the lens are based on a very low standard of focus appropriate only for small prints.
My goal is prints 20 to 43 inches high in the vertical, so focus matters more than say for publication or web use, for which even a non-tilting, pathetic, auto-focused zoom lens could be used with a single exposure.
John, thanks for the info on Hartblei!