Ask HN: How do you know if a tweak to your AI skill made it better?

Curious how people here evaluate changes when they tweak an AI skill / prompt / workflow.

A lot of the time, a tweak might feel better in one or two cases, but it’s hard to tell if it actually improved the skill overall or just changed its behavior in a way that looks better for a bit.

Do you mostly go by intuition, or do you have some lightweight way to check if a tweak really helped?