@ OP,
Michael is the guy to follow here. Forget the film testing, just rate your film a bit slower than box speed for more of a safety factor. (FWIW, my ZS E.I. tests usually come out 1/3 stop slower than box speed.)
The important thing is to nail down development times. But you don't really need a densitometer for this either.
If you're printing traditionally, then find a scene with a wide range of tones in well-separated areas that fulfills the criteria of "Normal." Make several shots, keeping careful notes about your metering; where you place the shadow value and where all the other values fall. Then develop a negative at your starting development time and print it on the paper you intend to use most at an intermediate contrast grade (2-3). When printing, match the shadow value to where you placed it when shooting (yes, this is subjective, but how we meter and place is an important factor here). Make a straight print at this exposure, dry it down and sit down with your print and the metering notes. If things match up well, then you've come very close to an ideal "N" developing time. If the high values are too hot, reduce the development time by 20% and try again; the reverse if the highlights are too dark, reduce the time by 20%.
Make a print from the second negative in exactly the same way and evaluate it. At this point, you should have a handle on on or two development schemes (N, N+1 or N-1). Interpolate an intermediate time if needed and go out and shoot. Keep good metering notes and you'll be able to tweak your development times as needed when things go a little one way or the other.
That's really all you need. Keep in mind that you just have to get the neg somewhere in the middle of the available contrasts of paper you have available. Then you use paper grade changes, etc. to refine when printing.
Best,
Doremus
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