I can't speak for your experience without understanding your installation
. Getting less than a couple years out of a cable seems a bit short, assuming you are not using it for coastal but are actively cruising. It should easily last a full pacific crossing over two years for example.
Some issues that will increase wear...
1. 1/4 inch seems very thick, was it a purpose built cable or did you self engineer
Edit: just re read and 7x19 would be the correct cable thickness but see point #2
2. If self engineered any variation between the cable OD and Teflon ID will create wear points at all radius turns. The cable will saw through. This happens anyway but should be much, much more slowly wil a purpose built morse cable...
3. More than 360degrees of cumulative bend in all three dimensions will increase wear. It may sound like a lot but most installations are hard pressed to not exceed this in the whole length of cable
4. I used in last application and plan on using in this application 1/8" cable. Adding 50% to manufacturers guidelines for minimum radius for turns is a good idea, and trying to make the turns as large as possible is always a good idea.
5. Keep length as short as possible and keep travel distance as short as possible. This is a high frequency application and length, travel distance and bend all increase friction and wear.
6. Minimise load.
A. The vane will be very efficient, the trim tabs tend to not be so optimised
B. Make sure bearings are true and the tab moves freely. A good trim tab should move when you blow on it during a haul out
C. Proper trim tab to rudder size
D. Proper lever arm length to trim tab
For me the biggest problem in wear that I will have in my current
boat that I don't have a solution for is the fact that I have a huge rudder and I am unsure how the wear on the cable will be as it flexes slightly to port and starboard with the rudder...