Even if you were playing with a coach, the question of: "Why do I play so well with my coach and then I can't transfer that good play to a match?" comes up as a regular subject.
With a robot you work on specific techniques which may or may not come up in match play or playing with a human. It is worth using one. But it is also worth knowing that it is not how real play in table tennis occurs.
You have to play a lot of different people and adjust to how each different person plays. Because it is not just that the robot doesn't hit like a person. No two people hit quite the same.
NextLevel's point about seeing some of what you are doing is really worth while. With a tool like a robot you could be getting the ball on the table over and over and yet still be making the same mistake over and over.
Anyway, here is a video that I think helps understand the subject. I have posted this many times for various reasons. So has NextLevel. It is worth watching the whole thing. Maybe even more than once.
Sent from Inside The Chamber of Secrets by Patronus