Once, when my wife, Gail, and I were hiking the high meadows of the Swiss Alps, we saw two farmers cutting the high-standing mountain grasses with scythes, a hand-mowing tool that has been around since ancient times. Their broad-sweeping movements seemed like the synchronous movements of dancers.
Drawing closer, we noticed that both paused periodically and produced from their pockets something resembling a flat stone. Then in the same graceful manner, they now drew the stones back and forth across the scythes' blades. The purpose? To restore sharpness.
The sharpening done, each returned to the cutting.
Gail and I observed them repeat this process—cut and sharpen, cut and sharpen—several times: ten minutes (give or take) of cutting followed by five minutes of sharpening.
A dumb question: why waste five minutes sharpening the blades? We're talking here about 20 minutes of unproductive time each hour. Why not keep cutting, get the job finished, and head home at an earlier hour?