As my last edit on this went pretty much unnoticed, I put it here again:
Considering the cost of walls, I am slightly concerned.
As it is now, plank is more expensive than brick, both in raw material cost and in time invested to make those materials.
As a rule of thumb, if you are making bricks for a wall of some 400 or more tiles, you will get all the sodom bricks (=expensive part) you need just by making the bricks you need anyways, which is totally ok, in fact, especially considering the dirt cheap cost of the lower walls, I'd say plank is simply too expensive, especially now that there are even 2 better walls and a 3rd announced.
Segments:
Plank: 1 planed 2 dry boards ~ 35-50s
Brick: 18 clay/bricks ~ 18-27s + 1 lard ~ 20s = ~38-47s
Starter:
Plank: 4 oiled 10 dry 15 planed 5 nails ~ 640s
Brick: 65 clay/bricks, 5 lard ~ 165-197 + 1 sodom brick ~ 300-500 = ~465-697s
Ok, the cost is actually closer than I felt, but yet you see that plank is roughly a bit more expensive than brick, which is bad.
Additionally, you will have a lot of "more work" and waiting time making dry boards, whereas you can produce anything you need for a brick wall right away, except for the gates, yea, I forgot the gates, at that point brick actually is more expensive than plank, but I still dare to say that if you are not spamming gates like crazy, the overall cost of plank is still higher.
This brings me to the point that our new walls costs are in no relation to the previous ones, I don't really want to say it's too expensive, but well, it is.