Block bookings

have you experienced difficulty in placing a booking at some CC sites?

i have had trouble getting availability despite trying to get an early booking.

having spoken to a friend he advised me that he books several sites for the same week then makes a decision the week before he is due to,travel based on weather/family choices etc. Then he cancels all the other sites..

should this be allowed?

Shouldnt there be a system in place on the CC computer bookings that would prohibit booking of the same period on numerous sites?