How often do you change the plugs on 2002 Mercedes-Benz S500

Just bought the S500 (MB) with 88,000 miles. Mechanic told me to replace plugs and cables. Did not notice any issues when driving.$790.00

Asked by for the 2002 Mercedes-Benz S500
2 answers
When you can tell it needds it! May have been done already, any misfire or run rough?
DO YOU HAVE ANY SERV RECORDS WITH CAR. IF YOU TRUST YOUR MECH DO REC, THATS WHAT U HAVE HIM FOR