Years ago, a company’s employee created a sale campaign on a Wednesday in late November, set it to begin on Black Friday, and then promptly went home for the weekend. By Sunday, someone high up in the company started to see messages on social media about the $100 wheeled loadout bags his company was selling on their Black Friday promotion. People were bragging about buying up to 10 bags per order. A quick calculation led him to the conclusion that his employer was well on its...