If you are talking about aircraft plugs no new ones failed but you have to document everything on the annual. When a plug went into a plane it has documentation. Hell, i had to document when i put nitrogen in struts and air in tires.
Had an engine years ago that you would only do that once. You grab the plug wire and I will turn the flywheel very very slowly. Until it clicked and you got hit with a full magneto discharge.
Must've had an impulse coupling.
When I was in college, I worked PT for a guy who owned a fleet of WWII bombers, patrol planes, and freighters (Douglas A/B-26, Lockheed PV-2, R5D, and Douglas DC-7) used as air tankers. Most had either the P&W R2800 or R2000; the -7's had R3350's. IIRC, the bottom cylinders used dual wire electrode plugs. Those Pratts ran so smooth you could read the engine data plates from the pilot's seat with the engine running. Of course, the cowls had to be off.
Wisconsin 7 hp engine with magneto ignition
The airport i worked at one summer specialized in servicing turboprob Aero Commanders and planes with radials. Since i was a high school kid i changed oil, serviced spark plugs, checked tire and strut pressures and washed planes. Saw a few R2800's and R2180's and others i can't remember. We did regular maint on a Howard 500. Nothing like an oil change that requires a 55 gallon barrel of Aeroshell 40wt. Per engine. That was almost 50 years ago.
Worked all 4 years of high school as a pinspotter mechanic at a small bowling alley. Went to the AMF school for 2 weeks when i was 14 and got certified. During the summers i worked other jobs. One summer it was at an airport in the maint hanger. Even though i wasn't an A&P mechanic they let me touch tools. Charlie Wells ran the maint hanger and he liked me. Used to take me to lunch in his 33 Duesenberg. The other high school guys swept floors and washed planes and painted stuff. After HS spent 3 years gathering intelligence for the NSA on on East Germans and Soviets in Berlin while I was a teenager. After than came home and worked 40 years fixing copiers and printers. Been running a mower shop on the side since the early 90's. I enjoy working on engines and equipment. I am retired so now the mower shop is pretty much full time.