I think it depends on the business you are in. If you are in 1 time zone and the people you are doing business with it could be mid day for them and 3 a.m. for you. So I think matters more what business you are. If you are running a corner brick and motor store yes mornings are when most sales calls are done at least around these parts.
I'm going to get started on the book tonight, see what his basis is