The quick answer....It Depends!
Where are your buyers located? I sell to the Americas and Europe primarily so for my customers the "business day" starts at 6:00am EST and runs to 9:00pm EST but this doesn't give any consideration for my Asian buyers.
I rarely do anything other than 7 day listings, I don't see the point of reducing the length of exposure time unless you have a very high level of sniping.
Just by default most of my listings are done between noon and 9:00pm EST.
Ben

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.