Editing time depends on complexity of topic, level of target audience, and aims for the Hub. Perhaps I spent the longest editing time on my Hub "How Colon Cancer Develops From A Polyp; How to Prevent Or Stop This Cancer." I had two big aims: to explain colon cancer and to prevent and stop it. It is a long Hub. I rewrote it three times. The hardest to explain is how colon cancer develops. The source, Cummings, used technical language that I had to level down to layman's language. His discussion is also concise that I had to do supplemental literature research. I had to recheck and recheck on the designation of genes.
I was fortunate to find an article by Dr. Oz who could explain colonoscopy better because he is a doctor doing colonoscopy himself and who was at the receiving end.
I am not so concerned about editing time. What matters most to me is my aim of getting my message across to my audience. In "Colon Cancer" I had to think of imagery like going inside the polyp myself.