It’s a matter of how much motion you have to start with. If something crosses the frame in 3 frames, chances are Twixtor will not automatically track that properly.
Your eyes are very sensitive to any small defects, at 10X slow down you have all the time in the world to see any little problems.
Net is not all shots are proper to extreme slowdowns. Sometimes with Twixtor PRO you can fix problems. Sometimes it’s hard. Say you have someone running facing the camera and the same action side ways. The shot where the runner faces the camera will be much easier for Twixtor as any point on the screen won’t travel as far to the next frame.
Pierre