Intensity=Pushing yourself to the limit

As a coach you always strive to iron out any technical deficiencies that your students have first, but how do you produce consistent results with technique?  How does your technique hold up under pressure, and do you sustain it when you're fatigued?  The only way to test this is to increase the intensity at which you execute your technique, there are a variety of things that occur when you're mind and your body are put under extreme duress and pressure, how well do you respond to these adverse times?  As a coach you know exactly when you're students are struggling with technique under normal circumstances, but do you know how to help them through these times.  Technique is corrected by executing movements over and over again, so that they become natural, and your muscle memory kicks in, and your mind begins to just flow through the movement without any excess thinking or strain.  You can give a player a 1000 forehands standing in the same place during a lesson, and it will definitely help, but it only helps them when they're stationary, what happens when you move them a little bit, what happens when you move them to the extreme, into the alley or off the court?  How do they respond?  If they can handle it in those extreme circumstances, chances are their results executing that particular shot under pressure and fatigue will increase dramatically.  In any sport and any athletic movement, there are various ways to improve, and there a myriad of coaching methodologies that are applied to help athletes improve efficiently and drastically.  Which method works for you?  Can we combine any or all of these methods to help cater them to your needs?  I believe that there is no one clear cut way to improve athletic performance, but there are some that work better than others, but I believe increasing the intensity at which you practice or execute any athletic movement will help tremendously, but this means something different to everybody, what does this mean to you?