Latter-day Saints are admonished to spend some portion of time every day in scripture study, with the family if there are children at home, but also in private. The practice is an ideal. If my own experience and the things I hear from younger people in my congregation is an accurate guide to actual Mormon practice, then this remains an ideal, especially in families with young children or children to be ferried to schools. We strive to meet that ideal, though many of us find it difficult to do so consistently.

But why this admonition? Mormon understanding of scripture is different than that of other Christians. We believe that anything given by a priesthood authority speaking under the influence of the Holy Ghost is scripture (D&C 68:4). Presumably the same thing could be said about other things spoken or written under the influence of the Holy Ghost, whether by a priesthood leader or not. But not all inspired writing is canonized scripture.

Canonized scripture is that which the Church has received as inspired and that it has agreed is a source of guidance and inspiration for human beings in general. What we have received and recognized as canonical through both communal wisdom and ecclesiastical authority is "profitable for doctrine, for reproof, for correction, for instruction in righteousness" (2 Tim. 3:16). The LDS scriptural canon consists of the Bible, the Book of Mormon, the Doctrine and Covenants, and the Pearl of Great Price.

But things could have been different. Some of the books that many call the Apocrypha could have been included in the Bible. The Wisdom of Solomon comes to mind. Other books could have been omitted, perhaps Philemon.

The same thing is true of the other Mormon scriptures. The Book of Mormon could have included the 116 manuscript pages that were lost. Or its original editors, Mormon and Moroni, might have chosen a somewhat different selection from the inspired works available to them. The Doctrine and Covenants has been revised a number of times, including or excluding particular modern revelations. In fact, as Mormons understand scripture, it remains likely that additional revelations will be added to the Doctrine and Covenants at some point. Presumably the Pearl of Great Price could also include more or less than it does.

We are not wedded to these and only these canonized books as the word of God. So why are we admonished to read canonized scriptures daily? Why not read any inspired writings, canonized or not?  

Because, we trust the tradition that began shortly after Jesus' ascension, when Christians began to collect and share with one another those texts in which they agreed one could find the inspiration of the Holy Spirit. Because we trust the tradition that began with Joseph Smith and that has been overseen both by him and by successive LDS prophets. Those traditions tell us that thousands, even millions of readers before us have found spiritual profit in these books. We have their witness that one can encounter the Holy Spirit through them.