Originally Posted by Brian Ratliff

I liken training to sharpening a knife. The first tool isn't a steel or even a whetstone; it's a file. Base training, the long 4-5 hour rides for an endurance cyclist, is the file, and I believe this at least partially a muscle building activity. Longer intervals like the OP is suggesting is the whetstone; the shorter and more intense those intervals get, the finer the grit. If you start training with too fine a tool, you'll get an edge, but it'll be fragile and won't last long. If you shape the blade using coarse tools first, you'll get a better shaped edge that can be honed over and over.