The filename date 03-04-26 can mean March 4 or April 3. It also says nothing about whether the date refers to an event, the contents, or publication. Files passed between people need answers to both questions. A useful date supports sorting, but it should not be mistaken for a complete revision history.
Year, month, and day
Year-month-day with a four-digit year, such as 2026-04-03, works well for a chronologically sortable naming pattern. Leading zeros keep months and days consistent. In an alphabetically sorted collection, those names follow date order when the date starts in the same position each time.
This is a useful working convention, not a requirement for every personal collection. Do not invent a day when you only know the year. A folder named 1998-summer-trip or a note describing an approximate date is more honest than assigning January 1. Keep estimated dates distinguishable from known capture dates.
Define the meaning of the date
For meeting minutes, use the meeting date. A record finished on Friday can still carry Tuesday's date if Tuesday was the meeting. For a regularly issued report, publication date may be more useful. Write down the choice so a later editor does not change its meaning accidentally.
The modification date displayed by the file system serves a different purpose. Copying, exporting, and saving can affect timestamps. Do not use that display as the sole evidence for when an event happened or a document was approved. The meaningful date belongs in the document or its accompanying description.
More than one revision in a day
Two releases on the same day need another distinction, for example 2026-04-03-schedule-v02.pdf. Timestamps down to the second are often unnecessary for ordinary project documents and make names harder to read. They can suit automatically generated data, but then the time zone and meaning must also be defined.
Try the pattern with files from two months and two years. Check sorting in the application you actually use and see whether the names remain distinguishable on a phone. Document important existing references before a bulk rename. Adopting a better convention for new work does not require a risky overhaul of the entire archive.