They can be important. It's important to know if you're flying to LHR or LGW (for London), esp if you're at an airport where planes of the same airline leave to

They can be important. It's important to know if you're flying to LHR or LGW (for London), esp if you're at an airport where planes of the same airline leave to both. Identifying the flight by flight number is often problematic if it's a codeshare flight (displays at the airport only show one or switch infrequently), so identifying by airport and flight time is easier.