There is a time to follow routine and a time to disrupt it. In the interest of fitness, we generally have perfect consensus that becoming more fit requires the disruption of an established routine, one that is perhaps followed for around 4-6 weeks at a minimum. (Other periods are training may be substantially longer, such as 8-12 weeks.) Do we see the delicate balance here, though? In order for a routine to be broken, it must first be established.
The role of music in our classes may at times be a guide. For example, we follow a cadentially appropriate (i.e., 80-100 or 60-80 RPM) musical tempo at times. At other points, a major development in the mass or texture of the music may warrant a surge or reduction in effort. This may be considered a form of routine -- that we feel almost led by the nature of the music.
Johnny originally contended that music serves to motivate our riding, as opposed to dictating it; however, it remains possible to remain true to the program, even while allowing the music to shape certain aspects of a ride.
Nevertheless, once my particpants are comfortable enough in their saddles, so to speak, I often disrupt the musical routine. I intentionally use music that does not have a tempo or beat in alignment with a given cadence (RPM). If I am feeling particularly contrary, I might even include music that is arhythmic, somehow improvisatory, or that has deemphasized percussion.
At this point, each rider is essentially forced to swim in a sea of rhythmic uncertainty. He or she is then in a position to become more certain of what a given cadence feels like, and to simply know that they are within 4 RPM of a specific target cadence. This is muscle memory. Clearly the best path in this context is to implement cadence checks, and so musical instability plus cadence checks may in fact equal cadential stability -- a relative certainty that the intended cadence (RPM) is actually struck.