Hopefully never... On my 2006 RRS, the passenger side front shock went out at about 100,000 miles, the front driver was replaced at 160K. But I did off-road the car quite a bit and ran with fairly heavy (300 lbs) rock sliders, which I am sure didn't help wear and tear on the shocks in the long run. The rear ones were still the original shocks when I sold the car with 210K miles on. Not sure there are a lot of alternatives to OEM out there, other than Arnott which recently introduced a set of high quality front shocks compatible with LR3/4/RRS.