Well I don't know about numbers, I just remember back in the days I used to harvest lots of tapes and bolts and find a lot of those, to the point I had enough of those for 2 upgrades but very few planks (this was before I joined this forum so I did not trade).So the general number is more or less constant, you just try to have plenty of planks cos you can trade better with them?
Maybe I'll give it a shot, but at the moment it is well balanced.
It was sooo painful having to scroll the paper every two minutes only finding 1x plank every now and then. Sure I also found better plank deals but once per day or so.
I then started trading my materials for planks, also land materials when they got introduced and was slowly building up my plank count. And know when I need to upgrade I mostly need tapes, and for some odd reason (well maybe not that odd) when I need a few to upgrade I can't harvest them and instead harvest planks and other stuff!
I have posted some screenshots of my paper today for instance. I recall a 7x plank (missed), a 5x plank (bought), a 3x plank (bought), 4x concealed, 1x concealed, a couple more from my followers, 1x from a toolbox, and a few from harvesting.
So I am definitely seeing planks more regularly. Of course, whether I get them or not is another story, but at least I see more of them!!!!
And now as a trade off I see much much fewer bolts in the paper