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While using forward lens tilt is common with normal and long lenses to increase DOF in landscape photographs, I wonder if it's used for those very wide lenses and their inherently great DOF. If not, it would seem to make a Pacemaker Crown/Speed Graphic much easier to use than a Technika for that purpose.
Tilting a lens does not change DOF it controls the plane of focus. The aperture changes DOF as does the CoC used.
Bill, I often find that the amount of tilt required with anything shorter than my 110XL is negligible. My fave lens is a 65mm and I rarely have to tilt!
Take a look at Jack Dykinga's Large Format Nature Photography. There are several examples of using tilts or swings with a 75 mm lens. Dykinga seems to prefer tilting the back, which is not usually recommended because it introduces converging or diverging verticals and other "distortions". But such things are less of an issue in landscape photography. Also, who am I to criticize a master like Dykinga whose pictures speak for themselves.
You are right that if you already have enough depth of field to get everything you want in focus, there is no need to use tilts or swings. But sometimes because of subject movement you may need to use a relatively large aperture. Suppose for example you are using a 75 mm lens and you can't stop down more than f/16. The hyperfocal distance will be about 3.5 meters. If you focus at that distance, everything from 1.75 meters to infinity will in principle be in focus. But suppose the nearest object of interest is more like 0.75 meters from the lens. If the vertical extent of the near objects is limited, tilting may help.
DOF and tilting:
It is difficult to compare DOF for a tilted lens to the case in which the standards are parallel. In the latter case, the region in focus, for an ideal lens, lies between two planes perpendicular to the lens axis, and the positions of these planes are given by the usual formulas (or tables). In the former case, the region in focus is a wedge shaped region which is "hinged" on a certain line at some distance below (rarely above) the lens. The angular opening of this wedge depends on the aperture (and coc). It is wider if the aperture is smaller. As the tilt angle approaches zero, the hinge line moves off to infinity. In any case, in the usual type of application where the hinge line is at most a few meters below the lens, the description of DOF is more complicated. Bob Wheeler and Merklinger have devoted considerable attention to this question. I described their results in www.math.northwestern.edu/~len/photos/pages/dof_essay.pdf The mathematics is interesting, but in practice one wouldn't do any calculations or use a table. A variation of the familar focus spread method (described in the above essay) works pretty well to determine the appropriate aperture.
Using very short lenses and tilts give you the opportunity for a vast range of scale in the picture - try filling the frame with an insect in the forground and your bust in the background.
I use wide angle lenses and tilts both back and front for as much distortion as I can wring out of the scene as well as as much or little DoF as I can get.
Now if I could only get enough bellows on my 4x5 Gandolfi to use the longest lens I could find (30 inch) to get the compression I'd like. And since I'm dreaming, I'd like some ISO 3200 black and white film in 4x5 and 8x10.
Like PaulO, I can't imagine needing tilt to change focal plane with my 65mm, though I have used it with my 110mm when shooting landscapes.
A limitation of really short lenses is that tilts, especially in the rear, can result in the lens banging against the ground glass...