I had a good run of oak but then the ones I planted seemed to have a much lower drop rate for seeds.

As I sailed around I would stop whenever I saw an oak tree and "wild" oaks were giving me seeds at the better rate. If there were two trees in a meadow area, one was bound to drop some seeds. No where near the rate of the planted ones.

This really could be intentional if they want them used more for decoration than mega finewood factories.