I just got off the phone with Delta; I will be flying to Juneau using Delta Award miles. When the agent said a flight number had changed on my first outward flight, I requested that they email me the corrected itinerary. My original reservations had been made in March; it is now the end of July and I will travel in about two weeks.
When I reviewed the Flight Itinerary, ALL my return flights had been changed, with no prior notice given to me by mail or email. Delta said it was because Alaska Airlines dropped the 1:00 AM flight from Juneau and put me on another which leaves at 4:19 PM the previous day. This was a complete surprise.
My earnest suggestion to anyone flying with Delta or Alaska Airlines is that they reconfirm ALL the flight information some weeks before they travel. I only found out about the changes to my flights through my own initiative, by calling the airline. If it had been the outgoing flight whose time had been moved up, I might have missed that and my entire expensive trip would have been severely and adversely affected.
And yes, besides stealing 8.5 hours from the end of my time in Alaska, the surprise change has of course made my total return travel time hours longer than it was with the original reservation. BEWARE! Your "confirmed reservations" may be subject to changes, and it seems to be your responsibility as the traveler to discover those if they occur.