Again I remember being at the store
When my Mom bought her Maytag in 1965. The salesman showed her the 30 second spin rinse between the wash and rinse cycles. He called that the first rinse. Instead of the 3 shorter spin rinses her old Kenmore had the Maytag had the 1 longer 30 second rinse prior to the tub filling for the "deep" rinse. My Mom was convinced that it had an adequate rinse. At least on a par with, or slightly better than, the washer she was replacing, so no need for a 2nd full rinse.
The only machines I remember from the 60's that had more than 1 rinse was the Westinghouse front loaders and our neighbors Bendix Economat. Since that washer had the squeeze tub, no spin rinse for that one. So I remember that washer having a dial on the front for either one or two rinses. The neighbor, Mrs. Graf, always had it set for two, which for a machine like that was probably needed. But I agree, no point in wasting the water or the time if you don't need to