Thank you sk - this does make it clearer :)
Though, I really hope you can perhaps explain a little on how you define the number of slots at an airport.
From my observation on Tempelhof, a "standard" length runway would produce 60 slots per hour. Naturally, airports that have two independent parallel runways (i.e. runways that are at least 1,525m apart from each other) would allow up to 120 movements per hour, like LHR and HKG. In the case of MAN (for example), it has two parallel runways, but since its they are too close together to be functioned independently, only 96 slots are available per hour.
When it comes to CLT, which has three parallel runways (plus one 05/23 runway intersecting the 18L/36R) that allows three completely independent approaches, it should, theoretically, be able to handle at least 180 movements per hour (should have been more because the intersecting 05/23 was not taken into account) - but that is not the case, why? The difference between 180 and 144 isn't small...we are talking about 36 slots per hour, that is 432 slot pairs per day!
There is one more thing that puzzles me.
You said CLT used to have 144 slots per hour when it only had three runways, and later reduced to 132. Both numbers look completely logical to me as I have absolutely no clue how many slots you add onto an intersecting runway. As long as it is more than 120 (which is the capacity of two parallel runways) it is fine by me. But then, when the fourth runway (i.e. the third parallel one, 18R/36L) opens, you only added 12 slots per hour to the airport. Correct me if I am wrong, but what you are essentially telling me is that this brand new runway, that is 9,000 feet long, that is parallel to the other two long runways, can only handle one movement in five minutes. I am sure the tax payers would want to know where all that money went :)
Thank you sk for reading this long essay ;) and for taking the time to respond in the forum. I would really like a logical explanation on why there are only 144 slots per hour instead of, say, 180, or 192?