I think you will find that the replacement cables will develop tiny meathooks (bigger ones concentrated in one area, can indicate a problem) almost immediately after installation. A more important, and oft overlooked, maintenance item in steering gear is the care and use of the wheel brake. If the wheel is left unlocked, particularly on a mooring or at anchor, the rudder will be working the cable and sheaves constantly--even if it is not really noticeable. Things get loose and work more. And then the cable can develop actual weakness at a point, sheave bearings get sloppy, and you can see a collection of meat hooks at one point, etc. I have never actually heard of a cable breaking, but I have seen situations where it was difficult to get things tensioned so that the gear would move properly in both directions because of wear in a slack system.