Grasshopper,
This is a great question since many new fly fishers don’t know when and why to extend their leader when fishing.
First, when using a 9ft, 5x leader, the 5x portion/diameter of the leader is approximately 24 inches give or take a few inches from the end. If your plan is to be using a 5x leader for the fly you will be tying on to it (remember the power of 3) then you want to make sure that the end of your leader or the “tip” or “tippet” is 5x. So if a 9ft, 5x leader loses more than two feet of leader material (it is now 7ft long) the end of your leader will now be around 4x diameter. Remember, that is not what you want to use – you want it to be 5x. BUT don’t wait until your leader is 7ft long because when you tie on tippet material you have to use some tippet up just to tie your double or triple surgeon’s knot. So my recommendation is to keep your leader no shorter than 8ft. Once at 8ft add more 5x tippet to keep the end of your leader at approximately 9ft-10ft and at a 5x diameter.
Second, here is a new technique to try out. Buy a 3x or 4x, 7 1/2ft leader and add a tippet ring to the end of it. Now you can extend your leader with any size tippet that you want to use. Just add 2ft of 6x tippet if that’s what you need or 2ft of 5x tippet, etc. Just remember to put your tippet rings on at home and NOT on the water.
