Minimum booking period?

mbee1

Left it quite late to book our longer summer break this year and struggled somewhat to get a pitch on some sites because the weekends get booked up. Generally there is plenty of availability Monday to Friday but then no pitches left for Friday and Saturday
nights beacsue of weekend campers.  

Would it be a good idea in (say) July and August to have a minimum booking of (say) three nights at the more popular sites?