Like others I have been using leaders right out of the package. I have read some articles regarding tying you own leaders. Ross Mueller in WI ties his own that finish somewhere to around 8 1/2' @ 3x. To that, he loops on 18" to 36" of 5x or 6x tippet. I read that John Wilson who guides down in AR takes a store bought leader, ties a perfection loop to the end and loops his tippet. I have experimented trying these methods with goof success. By looping your tippet you pretty much can use a leader for quite some time.

With that said, I intend to fish with threaded furled leaders next year. From what I've read all you cab loop 18" to 36" of tippet. Kathy Scott told me she usually adds a 3" to 4" pice of 3x to the end of her leaders and adds the tippet to that.