I had to go check my Shopnotes archive. That is exactly where I got the idea. I made my containers separate because it would be easier to handle modules and stack them; I'm not getting any younger. This turned out to be a good idea. I ended up adding dividers and additional modules to handle shorts of a similar length but narrower width.
IIRC I set the dimensional divider at about 10". This meant the large cubbies could hold cutoffs of the varying lengths from most material picked up at the lumber yard. The smaller 4" section could take those thinner offcuts that are still large enough to be useful for drawer runners and such but, that would make the larger cutoff area cluttered and difficult to sort through; DAMHIKT. An unintended beneficial side effect of going modular.