iSEO's checks aren't arbitrary. Each one is based on a published standard or documented guideline, and every result links to its source so you can verify it. The rule set mirrors Google Lighthouse's SEO & Accessibility audits — the same engine PageSpeed Insights runs.
Widely followed, but not mandated by any spec (e.g. Google rewrites titles freely and allows multiple H1s). We label these as best practice in reports so nothing is overstated.