Light Tippet for Winter Fishing
One of my favorite rivers gets tons of pressure all year and the fish seem to get very picky about what they eat and about leaders and tippets. A couple of winters ago I discovered that, especially in the winter, going down to 7X tippet, and even 7X flourocarbon tippet seemed to increase the number of takes I got significantly.
Most of the flies I fish in the winter are small midge larvae or pupae or other small nymphs so knot strength with light tippet is ok. Also, I normally wouldn't use such light tippet on larger fish, but I found that I was able to hold and land almost every fish and do it in a timely manner so they weren't exhausted.
Winter fish are a bit less feisty so if you are careful and use a light tippet-protecting rod like a 9' 3 or 4 weight you can land even big fish up to the mid 20 inch range (if you can find these of course). Give some extra light tippet and your favorite midge patterns a try this winter, I think you'll be happily surprised.