Tobes I think ypur struggling because your trying to make the CC system fit into the t'other
As I said earlier the "Dates Entered" and "Duration" is the deciding factor on what pitches are available, your scenario really needs an exceptional set of circumstance and isnt limited to pre picking a pitch as I've said plenty of pitches on CC model are not taken because duration of stay isn't available so "gaps" as you term do and will probably happen far more on a manual system rather than computer based.
In my 4 years going to the same site that had pitch pre booking I saw full occupancy pre summer which included pitch and store, tents, grass, hardstanding, fully serviced, large or small sized pitches and seasonal.
Not struggling. The CC system works with start and end date, but doesn't offer a specific pitch (just a pitch type). There is 0 difference between a computer operated system and manual system other than ease of use for both booker and bookee.
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Imagine you have a CL or CS with reservable pitches (top diagram). Blue represents nights already booked. 5 separate campers try to book space in order green, orange grey purple red and yellow. Green asks for 6 nights from the 4th and is offered 2 possibilities A and B. C D and E are already busy. She likes A and books it for 6 nights from the 4th to the 9th. Then along comes orange looking for 5 nights from the 5th - again 2 possibilities open, B and C. He picks B. And so on. Eventually Yellow takes a look at the site and asks for 5 nights from the 3rd, but the site is full. It has no possibility of a 5 night stay without moving pitch.
Now execute the same process, but without specific pitch reservation. As each camper requests a pitch, the only requirement for the booking system is to see if one of any of the pitches is free that night. If the answer is yes, then a booking is accepted.
On the day of arrival (3rd), yellow arrives to find 4 pitches occupied, and one free. They pitch on A. The next morning the occupier of B packs up and leaves. Green pulls on site and finds a free space and they pitch, and so on. On the 8th, Yellow has completed their stay, and move on leaving the site free for Red to occupy.
Booking a specific pitch offers fewer spaces over all IF you allow free constraint over start date and stay length. If a site is popular enough, you may find individual campers prepared to modify their own needs to fit in (I know we have in the past to get onto certain CMC sites), but does make the possibility of stranded pitch nights much more real.