Even if you just use a hooklength 1lb lighter than your mainline mate, it'll make all the difference!
Another thing to consider, say for example when using say 3 or 4lb line for float/feeder fishing, on some venues you might not get too many bites, and you might have to go lighter!
But if you use say 2Lb line for chucking a feeder out you'll struggle with the line getting damaged and crack offs on the cast etc etc.
Use the bottom knot, the water knot on that page, it takes 20 seconds to tie and will get you loads more bites and save you loads of kit, honest!