Back in the day when emissions regs were getting a lot tougher GM developed the HEI and used gaps as big as 0.055". It decreased unburnt hydrocarbons.
Drag racers found out that running a larger gap made them go faster if the rest of the ignition system could handle it. The advice was to open up the plug gaps until you started going slower, then back off a little.
If you think of the starting point of the flame, anything you can do to make it start bigger is a plus. Big gaps do that.
R.