Dang. Another bunch of rules to remember, so that I can break them.
Why should three's have all the fun? We can generalize the rule to the rule of primes. Eleven zones in the zone system seems too restrictive. Let's add another zero to that and REALLY fine-tune our exposures. And the "f" is over-represented in photography. We need to give equal time to the "g" and "h".
Let me add "The 86 Rules of Boozing". I figure there might have been 100 rules originally, but you know how after a night of boozing some of the money in your wallet seems to be 'missing'?? Same story here I suppose...