I believe it was required to recite all the canonical hours. By the way it isn’t the “ancient use” as the 1960 Breviarum Romanum psalm schema was basically defined in 1910 by Pius X and was a major rupture with monastic practice. The truly ancient use is the Monastic Office, the basic layout of which was defined in the 6th century, and is still in use in a post-Vatican II version by Benedictines (that is, the psalm schema is the traditional Benedictine one, but the calendar, collects, etc., are all post Vatican II)
That said, I believe many “tricks” were used: combining hours together; anticipating Matins and even Lauds the previous evening, and some priests I believe would say the entire day’s Offices in one sitting to “get it over with”.
This is one area where the post-Vatican II LOTH has actually tightened the rubrics. The General Instructions require that the verity of the hour being recited must be respected: Lauds in the morning, Terce mid-morning, Sext mid-day, None mid-afternoon, Vespers early evening, Compline before retiring for the day. Only for the Office of Readings is flexibility granted to say it at any time, and of course it is laudable and commendable to continue saying it as a Night Office (or very early in the morning, which is what I do)
The other thing is that while now, only the OOR, Lauds, one mid-day hour, Vespers and Compline need be said by those bound, the option does exist for the Roman LOTH to also pray two other minor hours using the Complementary Psalter, and for those still using the Benedictine schema, it is possible to pray Prime as well. Some communities still do.
So technically, even with the modern LOTH, assuming we define “day” as a 24 hour period rather than just the hours of daylight, it is possible to be faithful to the 164th verse of Psalm 118(119):
Seven times a day I praise you
for your righteous ordinances.
Just another small way in which the LOTH, contrary to popular belief, allows some continuity in tradition.