wow, will try that out! Thanks!
It is the opposite of Case 2. Case 2 makes AF stubborn to drop focus on a subject if the AF point goes off momentarily. Birders like using it because sometimes the bird moves unexpectedly.
I was tracking this bird and it put the breaks on and swopped up. It didn't try to re-focus on the water and all the shots through the burst sequence (10) were in focus. With TS at -2 you get about a second but at 10fps it makes a world of difference.
Case 3 is great for tracking two people running for example and you are switching between them.