What is the Shelly trick, and why is it profitable?
Every time you talk to Shelly and request a rucksack upgrade, her heart level increases a fraction of a heart – even if you don’t have the ingredients to make the rucksack. So, if you keep requesting a rucksack upgrade over and over, you can raise her heart level to 10 hearts in a day. This is useful because this means you’ll get maximum profit from working at the Tailor Shop.