For a long time I'd use my early changed oil as top-off oil for family and friends.
Sometimes it was very much needed.
The 4.6l F-150 (takes 6 qt,) which was clattering loudly on 3 takes the cake.
I'd always tell 'em, "You were low, so the oil you had got the $#!^ kicked out of it. Have it changed soon even though you're full now".
I cared that much. When people scattered I stopped doing it.
Assuming my catch pan was clean, which it was, it was an efficient thing to do.