My personal experience:
Before starting the robot, I have to re-arrange the chairs and make sure there are no dangling cables.
After vacuuming, I re-arrange back the chairs and clean the dustbin and filter.
In areas not accessible by the robot, e.g. corner, I still have to sweep the floor.

In the end, not much time saved compared to sweeping the floor.

However, vacuuming picks up more dust compared to sweeping.