What do stay-at-home wives (esp. the ones without infants or toddlers), who send their children to school, do all day?

Where I live, most of them have to work at least part time, ideally while the kids are in school and are home to resume childcare and perform all the other household chores.  
The idea that they’re sitting at home, still in their nightgown, their hair up in curlers, sitting in the couch, eating bon bons while watching TV is very much a stereotype of the past.  What did women do pre-Vatican II while the children were in the care of traditional sisters, brothers, and priests in good, based Catholic schools?  In the 1940’s and 1950’s, in cities at least, people had older conveniences like refrigerators, gas stoves and ovens, washing machines and dryers, vacuum cleaners. In the 1940’s cities, shopping required a bit more time going to separate stores for certain items like bakery, the butcher, the fish market, the green grocery. The full-service grocery and the supermarket came of age in the mid-1950’s, as did dishwashers.  In a luxury most of us no longer have, fresh, milk was delivered to our doorsteps. Same as today, clothing came readymade off the rack leaving only mending to be done at home. (Although fewer and fewer modern women don’t know how to repair clothes. With “fast fashion,” they’re more apt to throw clothes away and purchase new replacements. In the 1940’s there was the radio, by the 1959’s, a TV set graced most homes. Soap Operas were the staple of housewives. 
My mother wasn’t into soap operas. Once we were all in school, and even before, she belonged to a number of women’s organizations, the Republican Club, Ladies’ Village Improvement Society, The Rosary and Altar Society. She volunteered at a thrift shop run for benefit of St. Charles Hospital. Of course, she kept house, prepared meals, did laundry, mended and enlarged our clothes, in warm weather, tended the garden, managed the finances and business of our home. Once a week, she went for coffee or tea and light refreshments to one of the neighborhood women’s homes, sometimes hosted it herself. She was almost always at home when we arrived from school.  The idea that Mom sat home bored, wasting time, expanding her waistline is ludicrous. In warm weather, she hung the laundry outside to dry—-we all loved the smell of fresh, air dried linens and clothes. In the days before permanent press, clothing needed to be ironed. When we were babies, the days of Pampers, plastic, dishwasher safe bottles lay in the future. There were diapers to be scrubbed, soaked, scrubbed again, then washed separately from the other wash, bottles to be prepared in advance and sterilized on the stovetop. Laundry needed to be properly folded or hung, beds to be made right away with “hospital corners” on both sheets, flat and top. There were no fitted sheets with elastic.  
People were more well-mannered and had decorum. Rosary and dinner were done together and it was expected to present oneself washed, combed, and in neat, clean clothes. Children sat at the table until the meal was finished. Everyone helped clean up. Manners were expected. Gentlemen pulled out ladies’ chairs, words like “Please pass the……Thank you…May I be excused…Yes, No.”  We took turns instead of grabbing and reaching, there was no “Gimme, Yeah, I don’t like…Naw…Why not?” or just getting up and leaving. Pleasant and interesting topics were for dinner conversation. Nobody wanted to hear how, “Stewart Jones in 4th grade, he got the flu and puked all over the floor in the hall. Boy, it stunk up the whole school! You could smell it all the way in the music room!” 
Mom was in charge of clean up, but the rest of us washed and dried. Dad carried things to the counter and took care of items like roast pans, scrubbing out pots and burnt on items. 
Then, there were lunches to be made and packed for the next day. Once we were about 10, we were responsible to make our own, but always at a set time. High schoolers with jobs decided entirely on our own, pack a lunch, buy lunch. Forget lunch?  You were on your own. Don’t expect delivery service. 
So, no, Mom may not have homeschooled us, but was she idle?  Impossible! Men on a Navy and later, government salary didn’t have maids!  Even if a maid could have been afforded, we wouldn’t have had one.  

do you pray the divine office, little office or fifteen decades?

Five decades. That was pretty standard at the time. There was no division like today, traditional Catholic, sedevacantist, R&R, etc. You were just Catholic!  There were practicing Catholics and, especially after V2, when people began losing their faith, “not very religious” Catholics.
Before V2, many Catholics didn’t know their Faith very well. It was sufficient to trust and obey the priest, the bishop, the Pope. The catechism was learned by rote. If you didn’t understand it, well, no matter. You followed Catholic moral standards, most of which were shared by the majority of people, even non-Catholics. So when V2 came along, society was changing, the world was changing, and if the priests, bishops, even the Pope changed along with it, that’s what you did as a Catholic. The idea that the Church hierarchy would lead the flock into sin and heresy, it wasn’t even on the radar! 
Keep that in mind before commenting upon what my Dad “ought” to have done instead of a “measly five decades for little kids.” By the late 1960’s/early 1970’s, my family hadn’t changed a bit at home and other kids made fun of us for being “religious freaks.”