Russian Days of the Week with the Preposition по

Did you know that days of the week are used with the preposition по+Dative case in the meaning of regularity?

For example,

По понедельникам, по вторникам, по средам, по четвергам, по пятницам, по субботам, по воскресеньям

On Mondays, on Tuesdays, on Wednesdays, on Thursdays, on Fridays, on Saturdays, on Sundays