A couple of hours. But most of my Hubs are quite time-consuming. The one I'm about to publish (on how to write the I-IV-V-I chord progression) has taken probably 15 hours or more, and will take a bit more yet. (A lot of that is due to preparing the musical examples, especially the video examples.) Some have taken a good deal more than that, due to the extensive research required. (For example, for my book reviews I usually read the book twice through, making notes.)
And yes--that 'quickest Hub' is currently at 83. (It's peak rating I *think* was around 89 or 90.) It won't do well over the longer term, though--it's not 'evergreen.'