It is important to incorporate variety into your strenght training program, failure to do this will lead to adaptation to a particular movement. Over a long period of time performance gains will plateau even decrease . Do not limit yourself to a handful of exercises, variety is important to contimue a positive training response. You are not training to become proficient with one exercise like bench for example, you are training to be come a better athlete.
I don't completely agree, CNS fatigue and adaptation does happen but you can overcome that by dropping the particular exercise for a couple of weeks or even just by switching the order of your exercises.
