Thursday is generally a popular travel day for consultants on a "3-4-5" schedule. This is why cheaper fares often require Tue/Wed/Sat travel which are the least popular business travel days. Note that what is available for sale is not necessarily the same as fare bucket inventory on a flight. The cheaper fare classes typically have advance purchase requirements and will not be available for purchase same day even if there is inventory open. You need an ExpertFlyer account to check actual fare class availability for a flight.