I, too, always need to square up HST's. Primarily I suppose because I up-size them by the 1/8" (cut at the 1" mark vs the 7/8" mark). I use a different ruler but do as Jan in VA does. One of the main reasons I bought a rotating cutting mat. Makes the tedious job a tad easier. Gotta love 50% off coupons at JoAnns!