pictures are always great!
they reason i use the 1 inch greater, is i did a whole quilt in the HST's and i was cutting strips first, and the 7/8th was to hard for me..to do the continual cutting of the strips..it was either,find the next measurement back from the last cut, or move the strip back to the one inch measure on the mat,and measure to the 7/8th again...i found both to be tiresome. i don't like moving my fabric once i start cutting.
the way you explained is the way i learned also..