I have some Thangles but have never used them as I bought this book, my quilting bible:
http://www.amazon.co.uk/Rotary-Magic...9093476&sr=8-3 ,about the same time and use her method, measure up and trim down, for example 3 7/8" squares = "4, I then treated myself to this Eleanor Burns ruler
http://www.eleanorburns.com/shoponli...?i=24805&page= and have never had any trouble with doing HSTs fast and correct, less messing about than paper templates IMO