Only legacy airline I know of whose "same day confirmed" change allows to fly the previous day, is CO. As soon as you're within the 24 hour OLCI check-in period you can change to any available flight within 12 hours from then, even it it's the prior day. So if I'm on a 7:40am DEN-EWR-RDU Monday I can change to a Sunday afternoon flight.
Of course Plats have to pay $25 for SDC at CO, so it's not all wine and roses.
But that flexibility of prior day and 12 hours rather than 3 is worth it IMHO.