Funny what Beezageeza says re 'what broke?', 'cos I was just boasting the other day that the throttle cable on one bike was (note the 'was') the one it came with decades ago. . . it didn't break exactly, it was just that the outer protective tubing cracked and let in water on a wet and freezing day, and the inner rusted . . . and got sticky . . . and was a pain.
3 points come to mind apart from the good debate over 'make-your-own' or buy new.
The first - if you don't mind non-original - consider a 'straight-pull' throttle - one where the bit that describes the tight arc around the handlebar is a short chain which engages the cable nipple and pulls it in a straight line along a slot in a bit of bar. My original one was called a 'Practica' - when the alloy body cracked from old age I was so miserable at the thought of having to use a standard one that I made a copy from mild steel and it's the dog's b*******. People accuse it of being off a japanese bike, very flattering!. I need to make another one for the A10.
The second, regular light oiling, and grease round the top of the cable, where there is always space for moisture to creep in. Grease, regularly smeared, is just sooo good.
And third, easy, lazy cable routing - even if it's not per maker's. 'Neat and invisible' has a lot to answer for, IMHO.
Parallel cables for clutch and throttle is v good sense. I always carry spares 'cos I've spent too much time over the years trying to get home when one has failed. Plus, as any fooool knows, if you have a spare with you, the thing never breaks. Same reason I carry an inner tube . . . I won'tneed it till the day it's not there. Groily