If your products fit nicely into perfectly square images and they look good as they are in your theme, then you can probably skip this recipe. For some themes or some types of products, though, it's really beneficial to change how WooCommerce crops your images. If you're selling ties, for example, it's probably worth telling WooCommerce to crop them so they're long and skinny.
It's best if you have already created a couple of products and look at them to compare how the Featured Image and the Product Gallery look on their product pages. If you see gaps around the images, you may be able to increase the product image size and take advantage of that space.