So despite their avoidance of training to failure, they grow bigger and stronger for their less than maximal efforts, a fact I couldn't ignore and one that kept me keen to keep at it. I will provide my opinion based upon my findings and beliefs as to why training short of failure produces results. When going to failure this might take up to a week or more, yet while shying away from failure it's been my experience that it seems to happen within days. This puts the body in a better position to cope and react rapidly to the stressor. It's stress to be sure, but far from the magnitude that failure inflicts, so it's within the coping radius and disrupts the system less.
Enjoyment is no longer in conflict with uncomfortable pain inherent in reaching failure.
Having less discomfort to contend with means you function better in daily tasks and aren't crippled to the point that you feel restricted or unable to indulge in your regular endeavors, a welcome relief for many who need to manually work for a living. The best part is the way the body bounces back, allowing another small weight increment to be added to each exercise next time around. It's the gradual build up of all these small advances that provide long term gains. Instead the slow but steady method provided by shying away from failure is both mentally and physically comforting, as you are seeing something worthwhile for your efforts, and that is repeated on a very regular basis, a reassurance you are getting something in return for your efforts. Even though it's been said that the last rep of a set taken to failure is the safest, that is only true if it is done using the same perfect form you should be using throughout the set.