Ah - OK. Never heard it in that form. Looked it up since and found it being defined as something pointless as well as what I thought it was. IE -

In connection with our life, the sawdust is like our past. Many people tend to get back on their past. They used to think back of their sad moments, regretting and worrying those moments that are over and done with. When you are doing this, you are merely trying to saw sawdust.And if you are doing it in some portions of your life, I tell you,you will never find happiness but instead you will live in a life full of worries and regrets!Don't be a prisoner of your past!

This quote is actually similar to the saying, "Don't cry over spilt milk."..Yes, this saying is a commonplace, a platitude.

In the context of this thread and my understanding of it, it did not make sense. In the sense of saying things over and over again, then surely everyone on this thread, apart from newcomers such as Guest, Dave, are equally guilty of that offence. Aren't they?