Well I've attended Auto Italia almost every year since the first one.
Originally their was only one entrance down the hill. This made everything slow but reasonably well flowed to wherever you needed to go.
In the early days the Heights was the public car park.
Later on the Heights was used as the 500 Abarth area and I can't recall when they used the Bridge access. Basically 3 entry points and thus conflicting traffic flows.
While we are on the gripe soap box AutoItalia has become soooooo big, Brooklands 2nd largest event of the year, there has been an ever increasing discontinuity in how the cars get spread around all over the place.
Several visitors who spoke to me this year were complaining that the real classics were scattered all over the place with cars you can see in any dealership show room. I think what they were trying to say was that with a show of this size, where they are happy to see all cars (new,older, classic, etc) they did not want to go on a treasure hunt!
I can thoroughly see their point of views.
When shows get to this size, with a year between each one, and the revenue generated, I personally think a little more thought and planning could go into the event.