As you beginning training you will discover what works best for you on a personal level, just like you will know when you need to switch it up. The reason people recommend the back/bis, chest/tris split is because the muscle groups are synergistic with each other and when you work one, you work the other. If you've found personally that after working one set of muscles to exhaustion that you still have the metal to push the other group to the max and are eliciting better results by doing so, then by all means do it. Watch your progress and switch it up when necessary. Best of luck and Happy Growing, just my .02
