Generally I ask that the vet call me if they find anything unexpected, but I let them know that they should proceed with extractions, etc, if they cannot get ahold of me right away. And so far my animals have had some teeth that are staying in, which generally the tech cleans while the vet calls to inform me of any additional work that may need to be done. So there’s little to no extra time under anesthesia even when I’m getting called.
I adopted a 9 year old cat (from my aunt, who had to go into a nursing home). My aunt had never fed him anything but cooked kidneys (shse cooked them herself). First dental visit he lost half his teeth, second dental visit he lost the other half, was left with just his canines. He did just fine. The gum disease he had was a result of never having been fed dry food at all. He lived to almost 21 years old.