Actually I have used the same line for 2 years. I want also tell you I have used the same line for 3 years. The line I am referring to is Tatsu and one of its properties is longevity. For casting reels I have used 12# and for spinning 6#. Also keep in mind that some,of my reels may see less than 10 outings a year and only get used for about 7 months out of the year. I am not sure if the results would change if I fished year round or some of reels were used more often. Nevertheless Tatsu is a great line and has a longer shelf life than other lines I have used.