Dear customer, being honest the clutch doesn't have a lifetime range specific like the timing chains/belt: It is more due to the kind of driving of each driver in a car.
It depends more on the use and handling of the driver and where he is. For example, if you are located in a mountainous area or where there is a lot of traffic in which you must be using the clutch at all times to be able to move and stop, or if the driver is very used to each time the driver stops, the driver keeps the clutch pressed instead of placing neutral, among other customs that use the drivers that quickly wear out the clutch, these uses make the clutch wears out very quickly.
The clutch replacement is considered a common maintenance that must be done every so often according to the use of the driver, the clutch system is made up of 3 important parts known as the disc, the pressure plate and the flywheel.
You can make the change only of the piece in malfunction, but I recommend you to always replace the complete master clutch kit, and let me explain why.
When one of these parts presents wear problems, this is a common wear and almost evenly, it means that the other parts are soon to wear out when one of them wears out, if it is not already defective.
To make these repairs in the clutch you have to disassemble practically all the transmission, which has a labor cost, so it is not worthwhile to disassemble the gearbox 3 times to replace only one worn piece each time, it is better to disassemble it once and replace the whole kit, if you think about it it is less the cost in this way when you replace the kit than when you replace piece by piece.
For this reason most of the spare houses not to say that they all sell the complete kit but not piece by piece of the clutch system.