Here in NM its sunup till sundown, you can be 300-400 miles from the house so all there is to do is hunt and like has been said the animals are there all hours off the day. Ive taken deer and elk mourning, noon, and evening.
I will hunt any time of day or all day, depending on what I'm after, my mood etc. I would prefer to be successful in the mornings so afterwards work is all in the light, LOL. However, if I had to pick only one time, it would be afternoon/evening during the "magic hour" just before dark I call it. Seems I have seen the most big boys around then... ;-)
When it comes to scent, there are basically two types; those that attract and those that mask. I've tried both on many occasions. There are lots and lots of "doe in heat" scents, designed to attract a big buck into range. I've also used a "cow in heat" scent while elk hunting.
Another scent would almost be better named as a "coverup smell". The main goal is to cover up human odor or mask it. Though I don't believe you can ever totally eliminate all human...