Every mature ruleset accumulates logic that no longer does anything. Here is how to find it in an afternoon, using the fire rates on the Analytics page and the Verify tab, and how to tell dead rules apart from rules that are merely waiting.
The new Verify tab reads your RuleSet without running it and tells you what is wrong: rules that can never fire, rules that duplicate each other, two rules fighting over the same value, keys nothing supplies, and input combinations no rule covers.