Heinlein's Third Rule

In his essay "On the Writing of Speculative Fiction", Robert Heinlein listed five "practical, tested" rules that he recommended writers follow. The rules are:

You must write.You must finish what you start.You must refrain from rewriting except to editorial order.You must put it on the market.You must keep it on the market until sold.
I like those rules. They sound simple enough and easy for me to follow... except for rule #3. Every story I've published has been subject to rewriting. I've even b...