As a shop without developer on standby, with auto-updates off we probably see a bug fix from a plugin in that first week - then go months without a security patch for an issue that could impact us without us being able to do anything.
The bigger risk is probably missing a security fix not getting a bug.
If I get a plugin update, I have an easy chance to close a security hole. So it's best I take the chance. But with auto-updates off I don't get it (for months). So I am at more risk of problems.