I have a book called "Frontiers of Space" by Kenneth Gatland, published in 1969. In it he shows where Boeing did a study to put a heat shield on top of a Saturn V first stage and parachute it into the ocean, to be tugged back to the cape. It would land nose down with the engines up out of the water. So reuse was studied. Also replacing the J-2 engine on the third stage with a plug nozzle engine for use as a heat shield to land the third stage. Third stage could have also been used as a SSTO vehicle for small satellite launcher.
So, landing and reuse was studied, but NO MONEY was appropriated by congress to make Saturn reusable. To me this would have been a cheaper upgrade than going to shuttle, and sooner. Heavier payloads, and more in space construction, earlier.
Now SpaceX is doing it, hopefully they will fly one of the landed stages soon.