Spark plug questions

S/A Seabee post10.

FWIW Ive been running the exact same plugs for 10 years and 100,000 miles;champion Copper.I have carried a spare set for about 8 yrs, still in the their boxes.Right alongside the spare Orange box,spare ballast, spare CV regulator,the Holley jet kit,the dizzy kit, alternator belt, DOT5,etc.