In most context, failure is a bad thing. However, in resistance training, training to failure or proximity to failure is a good thing. It is how our muscles grow. Why?
Muscle growth is driven by a concept that we call mechanical tension. Mechanical tension is what happens when our muscles create a high degree of force due the involuntary shortening of muscle fibers.
Take this example- when we are on the last hard rep of a bench press, even if you are putting in a lot of effort to push the bar, the speed in which you can slows down. The velocity is slower due to the involuntary slowing of muscle fibers from fatigue. This involuntary slowing causes high degrees of tension and loading, which then stimulates muscle growth.
Does this mean that you have to take every set to failure? No, because that would just cause increased fatigue in the nervous system which can affect the subsequent sets and our body’s ability to recover. After tension is created, your body will signal the process of protein synthesis to build protein chains that can repair damaged muscle and add new muscle. Protein synthesis can be created after a set to failure but can plateau if there is too much volume. Too much volume just leads to more muscle damage, not more protein synthesis.
An effective way to lift to reach proximity to failure without excess fatigue would be to do less volume. For example, you could do a couple of warm-up sets for a hip thrust, then after adequate rest follow it with a working set to failure. 5-8 reps with a heavy load are enough to get you there without having to additional work.
Don’t be afraid of failure- embrace it! It is how we achieve mechanical tension, and mechanical tension is how muscles grow.