If they are busy, you can expect interruptions and a shortage of time. Notice, interruptions and a shortage of time. Or, an unfocused session in which her mind is on getting you out the door and getting to the next one on the table.
If I sensed they are busy, before we even start, I tell them and the boss, “If you are busy I will return a little later”. That’s the last thing they want to hear. Once a customer is in the door, they will do anything to keep him. Interesting discussions have followed.
When they are busy, some of them can pretend and act like they aren’t thinking about the next one in line, but they are. When time is shorted, it sends a clear message.
The key is to be aware of the current situation. Even if you have been there many times, take note of the current situation. And, always have a back up plan and be willing to walk.