If you look at the toolboxes and workbench in the background, I reckon the average depth of deutritus is ~15cm across that 3.6m run. What can I say? I was busy.
I'd love those tool boxes, unfortunately the wife feels that they're a bit extravagant for my workshop or garage.
I have half a dozen cheap roller cabs with top boxes instead, and a couple of sturdy home made benches to work on.
I do put my tools neatly away when I've finished the job I'm doing, but until then, the tools will be piled up around the thing being worked on.