Along the same lines, I also find it useful to have a text log for each sizeable task I undertake. This could contain anything, notes of module structure, code & data snippets for testing, everything!
Like one of the top comments mentions, it acts as a node of knowledge within a wider system (graph) and I end up revisiting these logs more often than you would expect! It only gets better as you explore/document more and edges form.
I also think there could be a good opportunity to expand this to kitchen appliances too. Premium quality but really dumb. I would be a loyal customer