Toaster oven for anything over 3/8 inch, every time, color is just a rough guess at best.

Remember the first time it clicked for you? For a buddy of mine it was a little number guessing game, nothing fancy. He kept getting the loop wrong so the game would just keep asking forever, even after you guessed right. He sat there for two nights banging his head on it. Then he finally saw he had the check inside the loop instead of after it, and when that "You got it!" line showed up he actually yelled out loud. Funny how one small fix makes the whole thing feel easy all of a sudden.

Saying the brackets "kept sliding down the wall every time I loaded them up" makes me wonder how much weight we're talking about here. If the shelf was really sagging under a normal load, a binder clip seems like it would just get crushed or pop off, not hold things steady for 3 months. Clips are thin metal and they aren't made to take any real force, so this might be more about a light shelf that barely moved anyway. What were you actually putting on it?