Any one of our individual tools tells you about one thing — your meta tags, or your heading structure, or your images. A real page usually has small problems in several of these at once, and they compound: a slow page with thin meta tags and a broken redirect chain is a much harder page to rank than one with a single, obvious issue. Running everything together is how you catch that a fix in one area (say, page speed) might matter more right now than a smaller issue somewhere else.
How to use the results
Start with whichever card has the lowest score and the most issues — that's usually where the highest-impact fix is. Fix it, then re-run the audit on the same URL to confirm the score moved before working through the next one.