If your SEM campaign has high Quality Score on exact match but most conversions come from broad match variants, you'd probably rethink how you distribute bids rather than just rewarding the high-QS keywords. Exact match might look clean and efficient, but broad match is clearly capturing real user intent. I'd gradually shift more budget toward the converting broad terms while still keeping exact match active for control and brand precision. Then I'd mine the broad search terms for new exact match keywords to improve efficiency over time.