I, for one, have used the method suggested by Kodak in "Advanced Black and White Photography" (which employs their projection print scale) several times with various film/developer combinations quite sucessfully to determine a proper EI, based on a Xone I exposure. I find it quite easy to use (and reliable) for this purpose -- and you don't need a densitometer.(posted 9367 days ago)However, I personally have not found this method effective for determining proper film development times, as Kodak's book suggests. Instead, I have used the method advocated by Fred picker in his "Zone VI Workshop" (pages 34-37)which envolves visual inspection of a Zone VII print image.
I find that, whenever I choose a new film devloper combination (which thnkfully is too often) I need to spend several hours testing for EI and development times using these two methods. However the time invested turns out to be well worth it since it results in getting consitently properly exposed and developed negatives -- which (let's face it) is a prerequisite for sucessfull darkroom print making.