We build a customary routine to get through our daily lives. Wake up, shower, go to school/work, come home, repeat. In the gym, having a routine that your body isn't used to is great. But every few months, you will need to switch it up. Your body adapts to what its doing so it doesn't have to experience the pain/damage from it. That's why lifting a certain weight becomes easier over time. Garbear recommends switching routines every 2-3 months.