If you are getting tired wrists or sore hands when using a hand saw, you are pushing too hard and more likely to wander off course.
You've measured perfectly, you know which tool to use and how to use it safely, now you just need to be handy with whichever saw you are using and get a perfect cut to finish the job off nicely. 'Let the saw do the cutting' means exactly that. If you are getting tired wrists or sore hands when using a hand saw, you are pushing too hard and more likely to wander off course. Keep your index finger pointed down the length of the blade to help keep it stable and apply the minimum amount of pressure.