Just my idle thoughts (again)
Of course the use of the calendar – in this additive manner – to open boxes is really a no no.
(Though it could have been used here for a specific reason.)
The lowest box number would be 2 and the highest 43 on the following dates (for any year):
01-01-22 (01/01/22) > 01+01 = 02
12-31-22 (31/12/22) > 12+31 = 43
With most of the box numbers repeating each month.
Box 1 would not get opened nor boxes 44 to 763.
If needing to know the contents of all 763 boxes many would need to be opened in each of the visits.
Think of the amount of time it would take – 2 years at 1 box per day!
Sorry to ramble on . . . but, well, you know!