Short and Sweet
Slow evolution is not always the best way to go, and in fact, for percussion loops, such as drums or rhythm guitar, it works best to shorten one of the loops by a quantized value such as a 16th note. With that approach, you get a different rhythm pattern for each repetition of the loop. You might want to use the whole cycle or extract interesting individual loops as in the previous example. If you use a pitched part such as rhythm guitar, be sure to avoid chord changes, because each repetition shifts the chord change earlier in the shortened loop.