When flying from Richmond, Virginia to Ciudad Juárez, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Richmond Byrd Intl Airport to Ciudad Juárez Abraham Gonzalez Airport flight would often be abbreviated as a RIC to CJS flight.