The actual drilling can be quiet fast. The limiting factor is making sure it isn't so fast that it shatters the tooth. What will take time is bonding the fill

The actual drilling can be quiet fast. The limiting factor is making sure it isn't so fast that it shatters the tooth. What will take time is bonding the filling. My assumption is that for a regular cavity fill, the drilling will be a much smaller portion of the time than the filling bonding. You can see that in the crown placement video in the article, almost no time is spent removing the outside tooth. The actual spent time is building up the crown.