What does it mean that atomicity is a practice not a rule?

The goal is not perfect decomposition but steadily improving your ability to decompose.

Example: A product manager writes her first atomic note: 'Users abandon onboarding at step 3.' It is clumsy — it contains a claim without evidence, no link to supporting data, and a title that could be more precise. Six months later, her atomic notes look different: precise titles, sourced claims, explicit links to related notes. She did not follow a rule that made this happen. She practiced decomposition hundreds of times, each iteration slightly better than the last. The note she writes on day 200 would be unrecognizable to the person who wrote that first one on day 1 — not because she read a better guide, but because the skill of atomicity developed through use.

Try this: Write three versions of the same idea at three different granularities: (1) A rough capture — the idea as it first occurs to you, messy and unstructured. (2) A first atomic attempt — one idea, one title, one container. (3) A refined atom — precise title, sourced claim, explicit link to at least one other note. Then write a brief reflection: what changed between each version? What did the act of refining teach you about the idea itself? Save all three versions. This is not a cleanup exercise — it is a record of your decomposition skill improving in real time.