Our brain is tailored to ensure our survival, and while our sensory system allows a fine degree of perception, our brain “shuts off” irrelevant perceptions that are unsuited to our environment, to avoid overloading.
Consider the following example: the basic elements inside our eyes are able to discern a single lighted match kilometres away in pitch darkness/black (or so they say).
Side-effect: our brain and sensory system cooperate to avoid overloading during the day.
The main concept is: an increase in a specific stimulus that stays at the increased level for a considerable length of time results in reduced sensibility to the continued presence of that stimulus- i.e. at that level, it is considered a safe part of the environment, almost background noise.
This observation stands true not only for physical aspects, but also for other parts of our interactions with the environment; why should our brain build different schemas?
It would be simply too inefficient (and we have already enough inefficient left-overs from evolution, without our brain and body).
At the same time, repetition reduces the need to make a conscious effort (e.g. remembering a process) to produce a specific reaction to a stimulus.
The risk? If you have just a hammer in your toolbox, every problem becomes a nail