When I saw her, Arabella was wearing Prada and Victoria Beckham that, in her own words, she’d had “for years.” That reiterates her point: making smart, incisive purchases enables us to build wardrobes that transcend time. These maxims justify expensive purchases by equating the amount we spend on the durability of the piece.

The 30 rule is contrary to the hard-and-fast rule that other fashion editors I know abide by. Some say that if you will wear the piece you’re lusting after as many times as the number of pounds you paid for it, then it’s worth it. That makes it harder, of course, to justify digging deep enough into my pockets to buy a Loewe bag. Will I definitely wear a mini tote over one thousand times? Who’s to say. Will I definitely wear it 30 times? Absolutely.

These are the two shopping rules that fashion editors swear by