[geochronology]

This. When I structured the standups for our own team, I budgeted 15 minutes for updates and 15 minutes for open conversation.

The result has worked almost exactly as intended: there's breathing room to discuss issues or ideas that come up in the course of conversation, but discipline around keeping those conversations brief enough to stay on the rails.

IMO at previous companies getting told "this isn't the time for that discussion" really frustrated me. As the OP stated, these conversations never happened, and it's healthier to allow some time and space for people to talk off-script when they're all meeting together.