Tiffany,
To add to what Michele said, every CC volume can be used even as your fitness improves. Infact to me, what is special about CC versus cardio on DVDs is that you can use the same workout to progress and tangibly measure improvement in fitness level. As you get more fit, you will find you need to increase the cardio machine settings (speed, incline, or resistance) to do the same workout.
The workouts do get more challenging in terms of overall duration, how long you stay in "high intensity" zones, and how much shorter the recoveries are in the higher volumes. You can make earlier volumes very tough by using more aggressive settings (speed, incline, or resistance) during recovery than you would for the later volumes.
Short answer to your question: Yes, but the early volumes can be really tough, useful workouts for days when you want short cardio for advanced exercisers too.
~* Vrinda *~