Often we talk about the importance of staying consist with an exercise plan in order to make it as effective as possible. For the most part, that is true. One must exercise on a routine basis, 2-3 times each week, in order to receive a desirable level of fitness. An important point that is commonly overlooked is the importance of staying consistent with the exercises within an exercise program. Too many times the exerciser changes exercise modalities and never receive the maximum benefit from any one movement. A common example could be: during workout one the individual performs the bench press, to strengthen the muscles of the chest and shoulders, the next workout the push-ups is performed, the following workout the bodyweight dip is performed and the forth workout the dumbbell bench press is used. For the most part all of these exercises stimulate the same body area and therefore are equally effective for developing strength and stamina; however, each one has a unique learning curve which must be acquired before optimum muscular strength gains occur. What I mean by that is each exercise has a specific technique which must be learned and mastered before meaningful resistance can be used, and strength levels increased. As a general rule this takes about 8-10 workouts to occur. During this time you will notice a gradual increase in repetitions performed and weight lifted, this is mostly due to the brain and nervous system becoming efficient at the movement.
Now, a common issue among many fitness enthusiasts is the fact that boredom sets in very quickly when a workout is performed over and over for a period of time. I agree workouts should provide a variety of stimulus while still challenging the body. What I recommend in this case is to choose 10 exercises that address the entire body, lets say: leg press, db chest press, machine lat pulldown, barbell overhead press, barbell curl, leg curl, ab crunch, low back extension, db lateral raise, wrist flexion. For the next 10 workouts you will perform these 10 exercises in the same fashion each time. Change the order of exercises each time; make it as varied as you wish but work hard on all exercises.
What will happen is since the exercises themselves are not changing the brain and nervous system will adapt to the technique or the exercise and become efficient at the movement; however, the overall stress on the body will be ever changing as well as provide a great deal of variety. - Doug Scott, Strength Coach