Random plank #4 measures 64" x 96" at this point. I used 70 strips of Kaffe collective fabrics and 118 spacer squares (which = 5.5 strips). Around 20 of the strips were left full length (42-44") and the rest were cut into half, quarters, or thirds/two-thirds. This (plus straight joining seams vs. angles on the original) is what makes it into random plank instead of jelly roll race which is all full length (width of fabric) strips.
This quilt is almost twice the size of the jelly roll quilt and took me 6 hours and 5 minutes to sew it. That doesn't count the time of pulling out 70 different fabrics and cutting 1 strip off each of them.
I have a chart on this post which gives you an idea of how many strips makes what size quilt.