Is it cheaper to book a flight on a Tuesday or Monday?

I have always used the following strategy to find the cheapest flights:

• Never book on a Monday or weekend. Booking companies do charge more. So stay away from the Monday blues and the wishful thinking of weekend travel;
• I often book on a Tuesday and there is a bit of a discount; and,
• One thing you must do before searching is clear your history.  Travel website can track what you have been doing and you will be charged more.