Too Long; Didn't Read
The job of a harvester is to use an axe to harvest trees, and the axe will deteriorate over time. Assuming that the following's the expected performance of the axe: Fully sharp axe(extremely excellent effectiveness and efficiency; ideal defect rates) - 1 tree cut / hour1 / 20 chance for the tree being cut to be defective (with 0 extra decent tree to be cut for compensation as compensating trees due to negligible damages caused by defects) The axe becomes a somehow sharp axe after 20 trees cut (a fully sharp axe will usually be much more resistant on having its sharpness reduced per tree cut)