Coned off pitches

Having returned from a 10 day stay at Burrs CP site, i noticed several times during our stay, as pitches were vacated, cones were placed on some of the vacant pitches. Thinking a problem must've arisen with the pitches, only to find that later an outfit would arrive, remove the cones and pitch up. This makes it appear that pitches are being 'reserved'. If this is the case, it is most unfair when pitches cannot be reserved by members. does anyone have another explanation please?