A publishing panel at WorldCon talked about not pitching a novel until you’ve finished it, and only sending out the best possible draft you can write.
Right there is a fairly obvious problem… how do you know when it’s “good enough”?
Obviously you need to feel it is error free and be happy with your dialogue etc, but how do any of us judge that our work is going to appeal to an agent or editor? Unless you’re lucky enough to know an agent or editor so you can ask them, you probably can’t be sure.
It reminds me a bit of playing pin the tail on the donkey…