[Jim B]

Don't forget that the service/replace cycle of any part or assembly in a race car is established by advice or practical experience. Aluminum rods, ring and pinion, and all wear/breakage prone components have a car/engine combination specific "replace" number of runs to ensure a minimum number of failures and or loss of performance. Although a single additional run over a valid cycle number is very rarely going to result in a failure, adhering to a schedule is simply good procedure that results in fewer "surprises". A far as spark plugs are concerned they have been cycled in the past rather than properly cleaned and dressed because they were frequently part of a parts deal and were free. Once plug cost is out of pocket Adger's method is a good cost cutting procedure to lengthen (not eliminate) the cycle number. (As long as you are not paying retail shop labor rates!!! lol)
You want to be sure not to get to the point like the guy who took such long steps to save wear and tear on his $40 shoes that he wound up splitting his $75 pants.....a round loss due to falling off a few hundredths because of overused spark plugs would fall in that category.