If the clutch is slipping, then you can make it last for ages if you need to, just by matching engine speeds before using the clutch (except for 1st gear from a standing start, of course), and by using less power so it doesn't slip. Once it begins slipping, it heats up and the slip continues, so you have to ease off the pedal.
My original Bluebird had a slipping clutch, for about 2 years, but once it started, it never got any worse, due to my change in driving style
The danger of prolonging the lifespan of a worn clutch is that you can damage the flywheel, especially if the clutch fails suddenly at the end.
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