Hmm, maybe. However I think she didn't mention Mass on Sundays and holy days because that was already so obvious and so widely done by Catholics. In those days Church attendance rates would've been over 90% in Catholic countries, people took Mass very seriously. I think by emphasising on the Rosary she encouraged people to put time aside for the faith on the other days of the week. Many families might've said evening prayers, and maybe prayers at meals, but that'd be it. The Rosary however is a fairly long set of prayers, so by adding it to your routine you set aside a fair bit of time for faith, prayer, pondering on the life of our Lord and how to emulate him. It's an important tool to turn an only-on-Sundays-Catholic into one who really makes the faith a big part of their lives.