How often should you service your suspension?

Mountain bike suspension is high quality stuff, but it needs servicing on a regular basis to stay in premium condition.  Service intervals are different from product to product, and are dependant on your riding conditions, but as a general guide, your suspension should be serviced as follows: 

Forks:

Dust Wiper Service – 30 to 40hrs 

Damper Cartridge Service – 100hrs

Shocks: 

Air Sleeves – every 30hrs

Dampers – every 100hrs or annually.

Dropper Seatposts:

Every 100hrs, or as required.

Here's a couple great example of some MTB suspension that is worn out, due to lack of servicing.