I've got a question regarding how the Premium Ticket works when servers are maxed out (so all the time, I hear you say?

)
It is basically to help in a debate I am having with someone on the subject.
The way I thought it worked is as follows:
A PT user should be able to log on at any time regardless of traffic. The server will create an extra slot to allow the PT user to log on until someone leaves.
In certain very busy periods it is possible that a non-PT user may be disconnected as a result of the "Preferred Game Access" that the PT user receives.
However, someone else has claimed that this is not the case and that the server has an allocation for PT users and an allocation for non-PT users and one logging on cannot result in the disconnection of another.
Personally, I don't see how that would work, as what would happen if the PT user allocation is reached? Would they not be able to log on? Unlikely....
The way I see it is the server has a limit. If the limit is reached and a PT user tries to log on (and
must log on) then the only logical solution is that a non-PT user gets kicked.
I just want to make it clear that this is not a rant about the PT system and the way it works.
All I am after is some clarification as to how the system does in fact work. I have read some other posts (via the search facility!) that appear to support my original belief, but just wanted to see what further information I could get.
I appreciate it may be difficult to qualify the facts, but any further comments on the subject would be helpful.
Many thanks.