Budget is rarely wasted because of a “bad algorithm”. Usually the cause is something easy to fix.
1. No tracking
Without a pixel, CAPI or set-up conversions, the ads don't know whom to look for, and you don't know what works.
2. Audience too narrow
A few interests, a narrow age range and a small city, and the ads get expensive. It's often better to give the algorithm a broader audience and let the creative and copy do the filtering.
3. One creative for everything
Creatives wear out. Keep 2–3 variants in testing and add new ones regularly.
4. Changes every day
Every big change restarts the campaign's learning. Give it a few days and decide based on data, not on day one.
5. Slow replies to leads
People contact several businesses at once. If you reply a day later, they've already chosen someone else. Replying within an hour is one of the easiest ways to make each sale cheaper.