Yes, and even if a thread or two extends into the combustion chamber, it's a simple machining procedure in a lathe to shorten the threads. Carbon-caked threads can damage the cylinder head when the old plug is removed. On some of the race engines we built, we used a hand-held cutting tool to alter the gasket surface of the plugs to "clock" the ground electrode to an identical position in all the combustion chambers. That's really getting anal-retentive!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!