My parish, in 1960, was 7, 8, 9, 10, 11, 12, and 5:15 PM (intended for men who worked in Steel Plant on Sunday, but anybody could go). There was a morning Mass Mon - Fri. If there was a wedding on Saturday they had to be done very early, because the church had to be cleared for the crowds-yes-crowds for Confession. (Must have been lots more sin in 1960 compared to 2016, because they also had confession weekdays). (not intending that as humor, but sad commentary on 2016)
School children were supposed to go to the 9 AM Mass on Sunday, where the sisters would attend; and monitor. As that parish grew they had a couple simultaneous Masses in the school gym and the overcrowded church, till the new church was built. I don’t remember exactly when the “high Mass” was. I don’t really have a good recollection of the distinction, other than the choir (and priest) sang a lot. I wonder, did they have a choir at low Masses then?