firewood. 我问了ChatGPT，可以这么说，下面是它的解释：

Ask: If I say, “Sharpening a knife is worth the effort it takes to chop firewood." do people understand it?

GPT Answer: 

Yes, if you say "Sharpening a knife is worth the effort it takes to chop firewood," people would generally understand the metaphorical meaning behind it.

This phrase is a metaphor for the value of preparation. It implies that putting in the effort to prepare (sharpening the knife) is important because it makes the task (chopping firewood) easier and more effective. In a broader sense, it suggests that taking the time to prepare for something will result in better outcomes.

So yes, this sentence is likely to be understood as advice to prepare well for tasks in order to achieve better results or efficiency.