We have a huge white oak at work that produces every single year. I've been here 30 years. The white oaks on my hunting properties DO NOT produce every year. Not only that, but some will be loaded while others are not. Late frost and drought effect acorn production, as well as canopy. A tree with zero competition will produce more consistently than a tree amongst thousands of other tree's. Cold air sinks. Some tree's in low spots may have been hit by a late frost. Lots of variables.