Wasn't sure where to post this link, it is behind a paywall, but the headline should grab your attention:
https://www.connexionfrance.com/news/eu-entry-exit-system-flags-4000-schengen-overstayers/777268
Key quote:
"Mr Nielsen said the system had already logged around 17 million travellers, 30 million border crossings, and roughly 16,000 entry refusals in its first four months. Of these around a quarter were due to people being flagged up as having overstayed in the Schengen area, he said."