Nobody asked, but here’s how I would put it for an unhooked / untagged candidate, relative to where the sit in terms of test scores/GPA ranges at a particular school:
Below the 25th percentile: Really no boost at all
25th-49th: Slight boost (+5%)
51-75: Good sized boost (+15%)
76th&up: Big boost (+25%)
All approximate, and it is going to vary somewhat by school.
That averages out to big boost overall (+12%, which might be double the overall admit rate) but it is not distributed evenly. If you think you can add the average boost to your long shot 5% chance and significantly raise your odds by going ED, you are naive (in my opinion.)