Originally Posted by GlennR

It all depends in your riding conditions. If it's very dusty and/or you ride in the rain then you need to service it sooner.

I finally replaced the bottom bracket bearings after 4 years and the headset were fine and just greased. I've yet to service the wheel bearings. I have 26,000 miles on the chainrings and cassette, but I do change the chain when it measures .5 on the Park tool. Brake pads are replaced when the cleanout grooves are almost gone. Tires... They usually get cutup before they wearout. Cables... I don't ride in the rain and have Sram eTap so only brake cables.

You need to find your own intervals to do maint.