This video was posted on my clubs cycling forum, and it brings up some really good points
I think one of the points that it brings up, about knowing why you are doing a workout is really important. If you have a good reason to do a session then it will be beneficial, for your mind as well as your body. If you are just doing it just to get the miles in then it may be the wrong reason.
You need to know what your goal is and work towards that.
It is important to have a focus for each session, and when I plan workouts for my athletes I always describe the focus of the session. This works in 2 ways, firstly you go in to your session with a focussed plan, and you are also programming your mind to believe in what you are doing, so that when it comes to race day you will know that you have done what it takes to prepare your mind and body, remembering this will make you a better athlete.
It is a good idea to visualise your race whilst you are training too, think about how you will feel when you are racing. All of this will help prepare you for the big day.
There is no doubt that High intensity sessions will increase your fitness, but you must also do race appropriate workouts too, and in the study that is quoted the participants did high intensity (that means all out efforts) for 30 seconds until exhaustion, or worked at 80% until exhaustion.
I am believer in balance and variability. If you do the same sessions week in week out then you will not improve as much as you will if you progress, and work in different intensities, the more time you have to train, the more you can mix it up. You also need to know when to back off. Ask yourself, what benefit am I getting from this session? Sometimes its better to recover and try again another day.