Hobbits considered that the shifting of weekday names in relation to dates from year to year was untidy and inconvenient, so they arranged that Mid-year's Day (and the Overlithe in leap years) had no weekday name; this ensured that all dates in all years always fell upon the same weekdays. As the Shire Calendar was now perennial, Hobbits no longer needed or bothered to put the weekday in their letters or diaries.
One minor consequence of the Shire-reform was that no month ever began on a Friday. This led to the jest in the Shire of speaking of "on Friday the first" when referring to a day that did not exist, or a day upon which very unlikely events would occur. The full expression of this idiom was "on Friday the first of Summerfilth".