An audit sounds like a corporate exercise. It is really just reading your own data on purpose once a quarter.
The setup
Spreadsheet, one row per post, last fifty posts. Columns: date, format, pillar or topic, hook type, tag group, reach, saves, follows gained. Twenty minutes of copying.
What to look for
Sort by follows per thousand reached. The top ten rows are your actual product. Frequently they are not the posts you are proudest of.
Group by pillar. Average the performance within each. Usually one pillar is carrying the account and one is dead weight you keep making from habit.
Group by format. Check whether your effort allocation matches the results. Most people over-invest in the format they enjoy making.
Look at the worst five. Ask what they have in common. It is often a single identifiable thing — a hook style, a topic, a length.
The decisions
Kill the weakest pillar. Double the strongest. Move your tag ladder up or down depending on whether you are consistently ranking or consistently invisible. Write down all three decisions with the date.
Why quarterly
Monthly is too noisy to show a pattern. Annually is too late to act. Ninety days is long enough to accumulate signal and short enough that the conclusions still apply.