I have taken a number of Pimsleur® language training courses. The Pimsleur method is a system of delayed reinforcement of vocabulary (and some grammar) that has been used within the US Foreign Service departments for rapid language acquisition. The idea is that a word is introduced and the learner must repeat it -- perhaps within a phrase. Then, a short time later the word is presented again. And then after quite a bit longer (maybe 10 or 15 minutes) it is presented again. Finally, the word is made part of subsequent lessons for a while -- while performing the same process with new words such that each word is at a different portion of the language acquisition series.
This works -- or the theory of it works -- because humans have both short-term and long-term memories and the ways that information is stored has different processes. These are chemical and neurological. These procedures aid the transfer from short-term to long-term memory.
But repetition is also part of the cycle of humankind's works. Some are associated with mental processes and some with physical. Newsdesks at media centers have a circular file where a certain topic may be flagged for a new article (perhaps very similar to the last -- or perhaps incorporating new information) about a topic to be created and presented every so often. Perhaps once every five years. Perhaps annually -- especially if it pertains to an annual event (Christmas, 4th of July, Bastille Day, Thanksgiving, Boxing Day, spring planting, ...) Some might remember the previous article, or articles, on the subject but many more will not. Thus, it is useful.
There is, of course, unnecessary repetition. I find that I tell people certain stories, or talk about certain topics, more often than they would prefer to hear. It isn't that I am trying to pester them -- I just don't know to whom I have already relayed the stories. If you are at the brunt of such, try to be patient as it is likely to happen with you as you age and there are more and more people within your life.
There is also repetition of physical items. A city manager will have a map, or maps (nowadays probably digital), of the road systems or water systems or sewage systems that provide the lifelines of the community. Certain roads, and routes, will be flagged to be repaved every so often. Presumably, more heavily used roads are repaved more often. Less heavily used roads are repaved less often. Some roads, and routes, are not on any systematic cycle of repaving. They are paved only after a certain amount of active complaints or if people, who have the ear of someone important in the local government, complain. It is unfortunate, but true, that roads through areas of less income often fall into this latter category.
The same can be done for water pipes or sewage lines -- but, because wear and damage is usually not obvious to detect, they typically happen only after some incident makes it necessary. That is why they tear up a road recently repaved in order to do water pipe renewal or repair. They aren't quite as unknowing as they appear -- they just value cost postponement over avoidance of undoing recent efforts.
Another area of repetition is that of fashion. Fashion is a supplemental design factor to most items -- clothing, appliances, home decoration, etc. As such, the choices do not usually affect the functionality of the items -- although it is often true that fashion will value form, or appearance, over practicality. That avocado green appliance that you had in the 1960s may have a turn again at some point in the future. Will the leisure suits of the 1970s make another appearance? What about those 1940s shoulder pads in women's jackets and blouses? Who knows? But fashion designers certainly are willing to reuse something that was once popular.
There is also something which might be considered repetition but might better be considered a premature attempt at introduction. Apple's Newton® of 1993 might not have been of great significance but the iPad® of 2010 certainly has been.
Even these blogs have topics that occur more than once. I have been writing them for 16 years. Even if I do a search through my blogs, the keywords may not be the same for the same general area. But, like the case with the news media, some topics may also be worthwhile to present every once in a while as they are topics which persist and for which new audiences may benefit. (Or perhaps I am just rationalizing my desire to talk about them.)
Repetition can serve various purposes. Some are annoying. Some commercial. And some very practical.
