Eight months of daily and weekly entries in a journal turns into something nobody scrolls through. The texture is in there, but the index isn't — and pattern reading means scanning across the index, not re-reading every entry. The fortnight rolling summary is the cheapest possible index.
Every fourteen days, before writing the next entry, scroll back through the last two weeks of entries and write a single one-line summary at the top of the current entry. One line is the discipline — not a paragraph, not a list, not a re-narration. Pick the one thing that mattered across the fortnight. 'Energy steady, two queasy mornings, sleep fine.' 'First week light-headed late afternoons, second week settled.' 'Uneventful, six dose days on time.' Three reasons the fortnight cadence is the right one.
One. A week is too short — most patterns don't surface in a week, and a weekly summary becomes a re-narration of the week rather than a compression of it. A month is too long — by the time you're writing a monthly summary, you've forgotten the second week's texture and the summary is biased toward whatever week is closest to the date you're writing it on.
Fortnight is short enough to remember accurately and long enough that something genuinely worth summarising has accumulated. Two. The fortnight summary is what your prescriber appointment prep actually starts with — most prescriber appointments are 8-12 weeks apart, which is 4-6 fortnight summaries, which is 4-6 readable lines that capture the whole interval.
Fortnight is short enough to remember accurately and long enough that something genuinely worth summarising has accumulated.
The two minutes of prep on the day of the appointment becomes 'I'll scroll the summary lines' rather than 'I'll re-read 60 entries'. Three. The summary line is also where future-self future-proofing happens — the entry from May becomes legible from November in a way the underlying daily entries don't.
By month six the daily texture has blurred but the summary lines stay sharp. Organisational note: this is bookkeeping, not medication management. The journal entries are still your prescriber's call to interpret.
The summary line is just the index that makes scrolling back to the relevant fortnight findable rather than buried.