Your script works on your laptop. This one-pager is what to check before you schedule it, so it still works on day 8.

A one-page checklist for the three things that kill scheduled Python → Google Sheets scripts: the 7-day invalid_grant token, 429 Quota exceeded, and duplicate rows. Tick the boxes before you schedule the job.

1. The day-8 token (invalid_grant): service account vs OAuth, the consent-screen “Testing” trap (refresh tokens expire after 7 days), sharing, the right Cloud project, key safety.
2. 429 Quota exceeded: requests vs cells, the 60/min per-user limit, one block instead of a loop, retries that are long enough.
3. Safe to run twice: keys, upsert instead of append, comparing dates as numbers (the unformatted / dateTimeRenderOption tip), RAW vs USER_ENTERED.

14 tick boxes, one page, printable. At the bottom: the Fix Pack, which has the code for all three (EUR 9).
https://whop.com/whop-0bab/python-google-sheets-fix-pack/