I don't know when to kill a side project or keep pushing

I have three side projects in different states — one shipped with zero traction, one paused mid-validation, one just launched. Every week I waste mental energy debating which one deserves my time. There's no honest framework for solo builders: launch metrics, time invested, your own conviction, signals from users, sunk cost. Everything online is either "never quit" motivational fluff or "always quit" lean startup orthodoxy. I want something that takes my actual numbers and helps me decide rationally instead of emotionally. Pretty sure every indie hacker has felt this and just guesses.