The original ones do last a long time. When my 74 144 was our only car from 1974 to 2001, we probably went thru 3 cables, average about 9 years/cable regardless of use. However, I noticed that the aftermarket ones last slightly more than 5 years before they'd break.

As a precaution, I replace mine every 5 years these days. Sure it does cost some $$, but I guess we make it up by not having to change the timing belt on the motor every 5 years or so... :)
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...and the bricks keep on rolling