To play devil's advocate -- when I look at that quilt, I think to myself -- hmmm, I wonder if I could use that charm pack and the jelly roll that have been languishing forever in my stash. It looks like you could use a 5 inch square, but, hmm, maybe I'm wrong. Maybe that starts with a 4 inch. Kinda hard to tell from the photo. And I don't want to have to buy yardage. Also hate cutting a charm pack down to 4 inches, since I lose the benefits of using precuts and basically waste over 20 % of the fabric. I know, I'll just ask my FB friend what size the starting block is. . .
Honeslty -- I would not buy that pattern unless I was a rank beginner and wanted my hand held. Even then, patterns and craftsy classes are a crap shoot. Occasionally one is very well done and provides useful insights, but the vast majority I've come across are disappointing, not particularly accurate, and don't offer any details or tips beyond basic quilting directions.
That quilt is nice, but it's very easy, and it's by no means an original thought. It doesn't really matter what the specific block and strip sizes are-- you could make them pretty much what you want so long as your math is right. If the pattern/tutorial offered multiple finished size quilts together with fabric requirements, a variety of alternate settings, several detailed quilting motifs -- then it's sale-worthy. Otherwise, it's nice to look at for inspiration.