If it was QR10/hour many will not use the parking facilities, which would make more space available.

Many of those who go there for a 6-hour woman-watching (just like bird-watching) need to think about the QR60 they're paying, and many they would think it's not worth it, park elsewhere, and walk.

2-Hours free would incite people to go out every 1h59m and come back into the parking. 15 minutes free (like at the airport) would make dropping or picking-up somebody free.