When you want to number the pages differently than the standard correlative, for example with a date system, weekly, monthly... There is no automatic option for the pages to be numbered by day of the week. If in addition to the options 1, 2, 3... 01, 02, 03... a, b, c... i, ii, iii... you add a "custom" with a popup to a list of... for example 20 custom fields (for months, weeks, work groups, jobs...) would be perfect.