Mild counterpoint: Not all dealerships are as bad as the horror stories I've read here.
I didn't know much about this whole process when I started down the road to buy my 5BW. I must have lucked out and dealt with a salesman who at least was aware of what he didn't know. After a little bit of conversation he fairly quickly and professionally said, hey, let me introduce you to our general manager because he'd have a better idea about whether we expect to get any of those. The GM did know about allocations, and said I'd be in a good position to get one given their allocation expectations and my place in line there (and it worked out that way).
I think more salesmen should take this approach, realizing when they are in over their head with a certain type of customer looking for a particular car. FWIW, this dealer family also has a Chevy franchise next door, so they were used to Corvette allocations at the time (when I initially said there was only one car I was looking at, they first assumed I was asking about a Corvette!). And that family of dealers has a Porsche dealership next door to that, same story.
Advice: If the salesman at the dealership does not know about allocations, ordering, etc. then the customer should directly and politely ask to speak to someone who does. If nobody knows how to answer those questions, then go to another dealership.
In another bit of luck, I happened to be in the dealership in August 2021. For those who don't remember, that was *after* the initial batch of reservations had already long been spoken for, with people like
@Tall Steve ordering something like 7 Blackwings, leaving none for the rest of us.

But this was before we (or at least I) had any idea when the order banks would open again. Turns out, I walked in not too long after the order banks had re-opened, so I was in the right place at the right time. Welcome to the goat rodeo. Car was built in January 2022, aged in the snow for 5.5 months, then finally shipped to me in July.
One thing I forgot to add: When I did order the car, they put me with a different salesman, familiar with the Blackwing, and we went through all the options and I ordered what I wanted. He knew what he was doing, was familiar with the process. This dealership put me with the right people at the right time, didn't try to push what I didn't want.