How long do shocks usually last?

Here is a video on shock and strut life expectancy from KYB the supplier of shocks for most Toyota's.
On a practical note I replaced all my struts and shocks at around 100,000 miles on my 08 Prius when it was no longer able to be aligned due to a strut problem. I had waited a little too long to replace mine.

Here is the video

 

And you can get fully built KYB replacements from rock auto for about 120 each. That’s new everything, even springs ready to bolt in.

 

You have to be very careful replacing shocks with aftermarket ones as the car could ride very rough if the aftermarket ones don't match original specs.

 

How about road conditions? I'm thinking running high tire pressures, frequently going over speed bumps, pot holes, that sort of thing.