A single panel swap on a door where the track and hardware are still square is usually a same-visit job once the part is in hand. Where it slows down is sourcing - original-era panels aren't sitting on a shelf anywhere, and a match for hardware this old sometimes means a modern panel cut and drilled to fit, which takes a return trip.
We're driving in from Huntington Beach, about 12 miles out, so we plan the visit around having the right panel loaded before we leave, not guessing on site. If the damage turns out to be worse once the door's open - bent track, a stripped hinge, cable a panel repair job never should have been carrying - we'll say so on the spot rather than force a fix that won't last through the mild coastal-inland swings this area still gets.
Most of what stalls a job here isn't the labor, it's parts lead time on anything that doesn't match current stock sizing. If your door is one of the older ones, ask about that up front so you're not surprised.