That was what you expected to see in the 50s. I have seen those triple taps that screw to the wall and an assortment of other similar devices. I am not sure when the NEC started requiring minimum outlet spacing but one per room was very common in the post WWII housing boom so people were making up for it with these devices. Unfortunately they were typically run with 18ga zip cord but occasionally you saw "heavy duty" 16 ga cord. The only thing that saved us was the usual load was a lamp and maybe a radio or TV.
