I love shimmer trim (aka glitter trim) and washi tape! It's so awesome to have something that is quick, easy to use, and comes with adhesive attached! However, just like any other supply, you can become a collector and not a user.
When looking at your shimmer trims, make sure you don't go crazy thinking you need one in every color and print, you don't! Primary colors are the best choice, red, blue, green, orange, yellow and purple. After that you can fill in with pink, tan, teal, but don't go wacky. Even though we sell a fuschia, I don't think I've used it once, be reasonable! Look through your shimmer trim and be willing to give up bad colors.
Washi tape is super dangerous because it's everywhere now and in every print and color. You need to be hard on yourself with this stuff. Because it lasts forever you need to really decide in a no nonsense way which you really HAVE to keep. How much of that roll of Minnie Mouse washi are you really going to use? How about the roll that's Happy Birthday over and over again? Really? You're going to use all of that? Polka dots, yes....penguins, no. Stripes yes, cupcakes, no. Plaid yes, clouds no. Go declutter.