Reserving specific pitches

Apologies if this has been covered before but, we are currently staying at a club site and we are seeing pitches being reserved by the wardens by means of "Motorhome Using This Pitch" signs being erected as soon as the pitch is vacated, for no other obvious reason than they are undoubtedly prime location pitches. But not pitches near the washrooms, or larger pitches to accommodate larger outfits, just great spots on the site. Is this common practice, if so how does one go about about it? Or is it 'who you know not what you know'? There's a great pitch opposite us now, was vacated this morning by a Motorhome, immediately the warden came out and erected the Motorhome sign, it's now been taken by a car/caravan outfit and the sign is still there!?