I just GMed carpentry. It took me about 50k logs and about 2 weeks (I don't play very many hours per day and I only had 40k logs stored up). My technique was to make a box that was the best I could for my skill level and then put the wood in the box and make stuff that didn't take a lot of wood per item mostly weapons. I add more wood to the box till I am over weight. Once I reach my weight limit, I toss it in the trash and start all over with a new box. On the high side it was gnarled staffs in an ornate wooden chest. Surprisingly gnarled staffs seem to get the best gains for quite a long time even though the skill required is not too high. The last 2 points was from tetsubo in ornate wooden chest.