Until some moron ran a stop sign, I had over 35 years in auto repair...line, foreman, owner.
There were some interesting disserences in manufacturer. Like, air-cooled volkswagens...you wanted to remove the threads in the heads, you put Japanese plugs into them.
Seriously.
Heat ranges are a joke. Just because NGK or ND or whoever shows a chart where they match up with OEM...they never do.
For reliability, and to prevent comebacks, OEM type plus were always installed.
Your Asian plug might seem to run better...and in 1,000 miles a year, maybe...but seen too many that ra way too hot and had the vehicles come in on a hook.
If it calls for Champs, gets Champs. Oddly, Ford was Champ until beginning of 1968, if my memory is correct, then autolite or motorcraft. Did just what they called for. Kraut Cans got Bosch. General Misnunderstandings got AC.
My Jag calls out Champs, that's what it gets.
Silly as those 4-point plugs that guaranteed 20% more horsepower and 10% better mileage.
Or, as folks were wont to do during the 70's "oil crisis", drop the float and jet them down.....and really good until they burned a hole in the top of the piston or torched a valve.
Engineers. Figured what worked best. Don't see a lot of Automotive Internal Combustion Design Engineers here.