I believe there is a strategy to pitching. You have to know the target market in which you are pitching. Every media outlet does not have the same deadline. For example, HARO (Help A Report Out) is a major pitching inquiry pool for all national journalist, tv producers, authors, bloggers and editors of national publications such as Huffington Post seeking interesting stories. They place an inquiry and have a deadline to close out the inquiry. Once you have solidified a relationship with a journalist, tv producer, author, blogger and editors, the best time to pitch is on a Sunday. Sunday can be the best time to pitch; whereas, it is the start of a new week. Most likely, your email (you will send around 3 AM hour) will be seen first thing Monday morning. So happy pitching!