What can I expect at an Evaluation Appointment at Mayo Clinic

I have a rare autoimmune syndrome, and I’m scheduled for an evaluation on a Wednesday morning.
The neurologist I’m scheduled with asked me to come, but that’s all information I can get.
After a couple calls, all anyone can tell me is they don’t know what will happen after my evaluation, and I could be at the clinic anywhere from 1 appointment to 7 days.

Is this vagueness typical? Do the doctors truly not make any plans for patients until they see us?

We’re hanging pretty much everything on this place because no one can figure me out.

Is this trust well-placed?