One of my plans for Cataclysm is to make a goblin hunter, with the skinning and leatherworking professions. I never had any character with these professions leveled up beyond the basics. But I remembered from the little I did that you need more leather for the leatherworking than you get if you just level up skinning. So as my level 65 bank alt had one free profession slot, I decided to already level him with skinning and get some leather stockpile in preparation.
So I was looking for a list for what leather I'll need, and found this leatherworking guide. And in the total list of needed ingredients I stumbled upon the line saying I need 1750 Borean Leather to get to the level cap in leatherworking. Wow! Most of it is used to transform to Heavy Borean Leather, but as that is the only way to get the heavy version, there is no way past those 1750 leathers. At 1 Borean Leather per skinning of non-elite mobs, that means farming 1750 mobs in Northrend to max leatherworking.
Isn't that a bit much? Especially when Wrath of the Lich King isn't the most recent expansion any more, there are naturally less mobs killed in Northrend. Then leatherworking could become a serious treadmill in the 400 to 450 region.