Of course the weather continues to get warmer, nights less cool. Dwelling longer on the subject might reveal other factors for quicker warm-ups.
The main benefit of Iridium is the electrodes are less susceptible to erosion giving them 100,000 mile replacement intervals.
I've run'em in our H-D and Our Triumph thruxton, could not detect any difference, over standard NGK's . When they arc
the air fuel burns, its just a given.
Enfield's being prone to foul plugs on occasion are better suited to standard plugs.
also, I would be uneasy running a plug that has the tip broken off after an attempt to gap. There may be other damage that went undetected,,
the electrode could be compromised, causing it to fragment, raining metal into the combustion chamber,
respectfully Merrill