I have been told by fly shop personnel that it should be replaced once a year. But I think manufacturers and shops a good reason to want us all to replace our tippet once a year. I have several spools of tippet I have had for several years which I had in my float tube. But I have not been using the float tube for several years so I am now using it. I do not notice that am having any unusual break offs or a significant number of break offs.

Having said that I a couple of years a go I did have a spool of 6x tippet that was breaking a lot. It could have been no more than three years old but I have no idea how lon it had been in a fly shop or what fly shop it was. After switching on and off with another spool of 6x I determined the 6x was bad and threw it away.