It is surprising how small the terrain effects are for many units. Pikemen don't seem to take much of a hit for being in the woods and they get a bonus for scrub? I would think they would take a nasty penalty in the woods. Good luck swinging that pike around in woods or scrub and your formation would be busted. The game has high attack, charge, and defense parameters so that many of the terrain effects are so swamped as to be inconsequential. This is similar to the weak mount effects values. Looks like an area worthy of some modding...