Practical uses for Circuits?

I've been playing Factorio for years and have accumulated tons of hours in the game. While I have a basic understanding of circuit networking, I’ve struggled to find situations where circuits truly shine and solve key issues in my factories. The Space Age space platforms have pushed me to experiment further, dealing with things like ammo counts, changing foundry recipes for red ammo to save space, and managing biters and pentapod eggs. I've found that working with circuits is a ton of fun! Recently, I’ve been trying to figure out how to practically incorporate them into trains or other systems. I’m hoping to see some examples of creative or advanced uses of circuit networking in Factorio. Can anyone share some interesting, practical setups or designs that use circuits? I'd love to hear get some inspiration to help the factory grow smarter!