Interesting observations these, I like them. I’m unconvinced that the Nottingham allotmenteer is gaining much by having progressively smaller bins, other than perhaps some space? I like the simile though and there could be other advantages I can’t think of. I make compost when time permits and I gather anything available; whenever this occurs it all ends up in the one bin by the following spring and is then used to earth up all my spuds, leaving the bed uber fertile post harvest. This method is then rolled across the plot, one bed at a time, each season.
Possibly overthinking things but not necessarily a bad thing – just don’t start deliberating over the purchase of a right or left handed shovel 😉