Filing and clocking has been around for a very long time. Back when I was a little kid helping out in my parents speed shop one of the first things they let me do was file plug electrodes, lol.

Now that plugs are centrally located in most combustion chambers I can see clocking loosing its popularity but in any offset design I'd concider it a performance given.

Combustion flame front propagation is critical to engine performance so its always good to have the spark gap aimed in the right direction.