While working we should also be continuously packaging our work into research, notes, brainstorms, examples, outlines, prototypes, drafts, todos etc. This is helpful for our future selves.
If we see our work as creating these intermediate packets, we can find ways to create value in any span of time, no matter how short. Productivity becomes a game of matching each available block of time with a corresponding packet of value.
By attaching value to small packets of work we are able to do something meaningful even in smaller chunks of time. This adds up in the long run.