The problem with these guides and rules of thumb is that they don't account for differences in engine geometry and the vicissitudes of running a modified production engine on a daily basis. You're also at the mercy of the knock sensor unless you change its monitoring range. So even if x AFR "should" work it may make the knock sensor go off, whether knock occured or not. And most people don't have the balls/wallet to turn off the knock correction.
Over time the cars that last are often the ones with the biggest safety margin in the tune or the ones that have a consistently working knock suppressant (race gas or methanol injection). I don't follow the "best torque" tuning strategy. It's too aggressive and leaves too much to chance when the weather changes.