I'm currently studying Andrew Loomis's "Creative Illustration" book. HIs other books which I've studied —Fun with a Pencil, Drawing the Head and Hands and Successful Drawing—have all contained so much helpful instruction that I've become a bit of a Loomis disciple.
As I explained in this post about Loomis's method for drawing the figure in perspective, his methods are sound despite his illustrations being sometimes convoluted.
But when I came across these pages in Creative Illustration, I had to actually question the method:
The first page shows formal subdivision design. OK, that's clear. The second page shows his informal subdivision method which is where he loses me. I tried it with a ruler and pencil yet every time I got even divisions! At first I thought I didn't follow the instructions correctly but after four tries I realized that it simply doesn't work. All of Loomis's examples show uneven, random divisions while all of my tries were even or symmetrical in some way.
Does Loomis's informal subdivision method work for you?