I'm under the impression now that it depends on what developer your using. When I was using Diafine, my speed rating went up. In fact I could get away with as much as up to 2 stops higher, although I found one stop the norm, and easily so. This was essentially an eyeball method, looking for shadow detail and highlights as well.

I shot some 4x5 Delta 400 this week and developed it in Xtol for a quick down and dirty test. First test was (believe it or not) as a stand developer. It actually worked, and second to compare, at a 1:2 dilution. What I did was to shoot on a sunny day with dark shadows and bright highlights in the frame. I stopped down the lens to give me a Zone 2 exposure ( or what my Zone 2 interpertation is according to A. Adams) where I wanted to see it and developed the film by the normal charts. Everything came out as I expected to see it and the 400 rating was right on. But the Xtol is a speed increasing developer, so if I was developing in someting else I might find the 400 rating to be actually lower. As concerns the stand development, it just need a little more time to bring the density up a little, but the zone two shadow was there as well at 400. Interestingly, the color of the stand dev neg was much warmer at 1:4 in comparsion to the agitated neg at 1:2. Hmmm.