For me, completing Grade 0 was a process of increasing my hatting as a PC. Although not trained as a Classed Auditor, I increased my awareness of my own sessionability and what sort of responses the auditor is looking for while in session.
I'm better now at deciding sooner, rather than later, whether or not I've got something relevant to the questions being asked, or whether I suspect I will find something or not.
I compare this sort of pc awareness to knocking on doors in the neighborhood: If you're ringing the doorbell for 20 minutes and no one is answering, no cars are in the driveway, the grass has not been cut for 3 months, maybe there is even a For Sale sign in the yard...guess what? No one's home! Move on to the next house!
When you know what to look for, it is easier to stop overanalyzing and 2nd guessing yourself. This should pave the way for smoother auditing on the next levels, 1-4, which I look forward to!