One anesthetic and one recovery is usually kinder. Past four hours of operating, the arithmetic changes.
Combining is often the safer choice: fewer anesthetics, one period off work, one set of garments. Complication rates start climbing with operative time, and the curve steepens after four hours.
So four hours is our ceiling in a single sitting. Anything longer gets staged, even when staging means a second trip, a second recovery and an unhappy conversation about the calendar.