Take a walk around your neighborhood at the end of a 50-degree late-winter day. Chances are that even if you had several inches of snow on the grass, it’s mostly or all gone now. But the snow piles–the three- and four-foot tile piles from driveways and sidewalks–are still basically intact, having resisted melting and soaking into the grass. The fact that all the snow has been packed in one place actually inhibits its soaking in.
If your choir rehearsal tends to feature sight-reading practice just in the couple of weeks prior to festival or contest, what you’re making is a giant snow pile of musical knowledge and experience. It might be impressive, but it has no time to melt and soak into your students.
If, however, you practice every day for a couple minutes, you’re spreading that musical knowledge evenly and gently across the entire year – and then all it takes is the right atmospheric conditions for all that knowledge to soak in.