How long do shock absorbers last until they need a service or replacing?

[electro_boy]

Wondering what the forum views are on shock absorber lifetime and if they need servicing or replacing after a while?  

Reading though the manual for my Evora I couldn't see any info regarding servicing the shocks on the car after a certain amount of time appears they last the lifetime of the car without any maintenance.  One of my hobbies is riding mountain bikes and the shocks on those are supposed to be serviced every X hours of riding, lubrication oil is changed regularly and damping oil and seals and o-rings are changed annually.  I was recently at the Lotus driving academy chatting to a guy who rode motorbikes a lot and he also services his bike's suspension every year.

So based on my limited experience I find it surprising the shocks on a performance car have no maintenance schedule, surely the oils break down or become contaminated over time and its beneficial to flush old stuff out and replace with fresh new stuff?

[EGTE]

My understanding is that dampers typically begin to degrade from about 60,000 miles. But that's an extremely generic figure.

[Gashead1105]

I believe the OE ones will last until about 5 minutes after you've saved up enough for your Ohlins/Nitrons/other preferred damper