Use the biggest size image whenever you can. The reason is simple: Design Transfer feature. I had a customer transfer my sticker to a large size wrapped canvas, for example. Of course, something like a canvas is rare, but I do get design transfers between products by a customer quite regularly.
Also keep in mind that some products, like blankets and yes, the stickers, come in sizes from small to large. Check if your image works on the biggest size, even if you are publishing the smallest. This gives a customer the most options 🙂
