Why these precise dates?
Because there's a very long tradition of paying rent on the Quarter Days, said my boss.
I knew from my time as a historical re-enactor (specialist period 1460-1485), these were four major religious feast days of the Church, so there'd be regular reminders.
So, on this #Michaelmas #MichaelmasDay all kinds of businesses are paying their rent on a feast day fallen into desuetude, wondering 'why today' & receiving that most unhelpful response, 'because we always have'.