Is this true?
It probably depends upon what you mean by the word “study”. Not all are called to be theologians or biblical scholars. There is such depth to Catholic teaching that you couldn’t cover everything even in a lifetime of study. But I think we are all called to continually go deeper, wherever we are. Of course, exactly what we can do depends upon other obligations (family, work, etc.), but we should be doing something, however small. Going to Mass helps!
I guess it depends on what is meant by studying the faith. Catholics are not obligated to study scripture or patristic writings or anything like that. They should be attending mass regularly and paying attention to the sermon.
In general though, there are many ways to grow in faith that do not involve studying in the traditional sense. I believe there are many saints who became very holy simply by devotion to daily prayer.
Consider for example, the Benedictine Monks. Most monks these days are well educated in theology, but even now it is not necessarily required. They should be able to read, but not necessarily for studying. They need to read for the Divine Office and for Lectio Divina. The latter is the prayerful reading of scripture and other spiritual works, not as a form of study, but rather to inspire praise of God.
So studying might be edifying to some (myself included), but for others, their simple faith does not require it and I think they might be the lucky ones.