The main purpose of a bra is to support your boobs. The secondary purpose, that many girls use it for, is to cover your boobs. Well, this is exhibitionist training, so I'm not very interested in the second use. So I only want you wearing bras that are needed for support. Which means, I want to set the number of days you get to wear a bra based on your cup size.
D Cup or higher: Wear a top-drawer bra up to 4 times a week, and a bottom-drawer bra up to 3 times a week.
C Cup: Wear a top-drawer bra up to 3 times a week, a bottom-drawer bra up to 3 times a week, and no bra at least 1 day a week.
B Cup: Wear a top-drawer bra up to 3 times a week, a bottom-drawer bra up to 2 times a week, and no bra at least 2 days a week.
A Cup: Wear a top-drawer bra up to 2 times a week, a bottom-drawer bra only once a week, and no bra at all for at least 4 days a week.