I once asked one of our top Canadian players the merit of playing 4th best, rule of eleven (subtracting from 11 to find the amount of cards that will be higher than the card lead) rule of , 3rd best, rule of twelve, 5th best, rule of 10.
However the most interesting comment made by this person was that one of the main reason he used 3rd or 5th was that many opponents are reluctant to learn the difference.
The moral is
"do not be reluctant to ask for explanation". Most bridge players take pride in giving a full explanation. I use 4th best but when checking ops cc and I see different leads I will often check my bible to see which rule applies. Can't remember everything you know. Hope I didn't post this message already.