That is El Burns method and it is so easy and you get perfect HST.
You also need the ruler that goes with it. Quilt in a Days triangle square up ruler saves alot of cutting since you lay it on the stitch line and make one cut.
By the way, the ruler comes with all sizes to cut for. It amounts to adding 2 in for each size up (8in for 3 1/2 in HST)
Thanks for that website its a good one.