I have been using a blood knot to join old line with new line for the past 3 years. I have never had a fish yet take me down to the knot. But I go more than half to maybe three quarters down into the spool before I make the connection. I fly fish a lot too. And I have that blood knot tested everytime I get a fish on. And I seldom had that knot break on either one of Yakima's finest or on an occasional Steelhead. When I have fish break off it's becuase of "ME" and not the knot or the line. I also own several reels. Some of these reels only get used once or twice a season and sometimes not at all. I keep the line of them unchanged because of the little use they get. Some of that line is more than 2 years old and maybe even 3. Use common sense and if you think the line is abused or if you don't have confidence in it then change it. But keep in mind that those who are in the tackle business would love to convince you and me that we need to go out and buy a new spool of line at least once a year if not twice. Let's see, $8.00 to $16.00 a fishermen a year times 1,000,000 fishermen around the U.S. is . . . Well, you do the math. And don't be afraid of using a blood knot.