Why is working to failure important?
Working to training to failure is important because it is how you get stronger and faster. That moment when you think you cannot do or accomplish another rep is the most important. Working to failure is what allows for the muscle fibers to micro-tear which in fact allows for the repair process. The repair process is by far the most important of the muscle recovery phases.
When you think you can’t do that last rep, try pushing a bit harder!