I'd say it's as close to gospel as it gets. I do believe it does discuss WOT vs. cruise. Metering rods have a step on them. When the fat part of the metering rod is in the jet, that's a leaner mix for cruise. When the rod pulls up and the small end of the metering rod is in the jet, that's your richer mixture for WOT. So the way you tune the split between cruise and WOT is with the metering rod.

Just like with a Holley, you don't want to run a really rich secondary and a really lean primary. One step of mismatch is OK, that's how you fine tune. If you get lost, always go back to what they put in it at the factory and tune from there, and get an AFR meter or professional help.