Tracking the funnel, not just the ad spend
Lead, contacted, quoted, won. If you don't see drop-off by stage, you can't fix the right stage.
Count by stage, every week
Four numbers: leads, contacted, quoted, won. Five-minute weekly habit. Reveals where the leak is.
Most leaks are in stage 2, not stage 4
Most shops obsess about close rate. The bigger leak is usually leads never getting contacted, or contacted too late. Fix the early stages first.
Adjust marketing based on funnel, not channel
More leads won't help if you're already not contacting half of the ones you have. Marketing without funnel data buys more of the same problem.
Take your version of this question further
This is one operator-tested angle on the question. Your shop, your size, your trade, and your team change the answer. Ask your specific version inside Ask a Shop Owner to get a response grounded in how owners like you actually handled it.