The scope of the Book of Mormon applies to societies and individuals. Read at the personal level, you see how by degrees people fade or fall away. The divergence is small to begin with, barely noticeable even. Yet it grows over time not only in the amount of separation caused by the different tracks, but the rate divergence increases over time too, like a hyperbolic arc.
For a long time, things appear normal, then BOOM! In an instant as it were the differences manifest in behavior which surprises most.
I think that principle can be applied to not only our testimonies, but to relationships. They need to be fed constantly. They need to be treated like the special things they are every day. It doesn’t take much, but it takes some effort, a little each day.