It depends heavily on your photos. Clear, well-lit faces match reliably after you've trained a person on just one or two reference photos. Side-profile, low-light, partially occluded, and body-only matches (people shot from behind) are inherently less confident and often end up in the review queue rather than auto-tagged.
The plugin is designed around the idea that you'll correct it as you go. After each scan, you confirm or reject suggestions in the review step. Sync Corrections then auto-tunes per-person tolerance based on that feedback. After a few scan + review + sync cycles on the same catalog, accuracy typically climbs into the 90–95% range for the people you've trained — and keeps getting sharper with every round.