Are the cases even that important when I'm using subject tracking?

[chnniten]

As I understand it they only affect focusing forward and back, not tracking the subject, so if I'm using subject tracking does it even matter assuming the AF point is over the subject?

I've found that I'll often lose focus on a dog that runs behind a pole or something, even with Tracking Sensitivity all the way to locked on and even if it doesn't lose the subject tracking.

[Waddizzle]

Welcome to the Canon Forums!  What camera are you referring to?

I am not sure what you mean by “only affect focusing forward and back.”  Autofocus Cases configure the AF system if several different and subtle ways.