The manual calls for inspection of the plugs at 24,000 miles and replacement at 48,000 miles.
The thing about motorcycles is they require more attention to detail when working on them than cars, because a sloppy mistake on a car is likely to be an inconvenience, while the same mistake on a motorcycle can be fatal. Granted, this isn’t the case with spark plugs, but I have higher standards and expectations for a motorcycle mechanic’s attention to detail than a car mechanic’s.
If I spot shoddy or half-a##ed work on my bike, the mechanic or shop who did the work will never lay their hands on any motorcycle I own ever again. I’m a lot more forgiving when it comes to my car, because there is a lot less at stake.