The arithmetic of the 26 sites

The PA is leasing 26 sites from the HDB for community events. How long is the lease and how much would it cost the PA for the lease? The next question is the number of days that these sites will be used.

If the usage of the sites, averaging once a week for each site, it will mean that the sites will be unused for 365 - 52 days or 313 days. Double the usage to 2 days every week, ie Sat and Sun,