When doesn't reuse make sense?
While you should try to reuse as much content as possible, there are times when reuse is inappropriate. Not every piece of content is reusable, nor should content be reused when it is inappropriate in the context in which it is being reused.
Sentence fragments and individual words may not be appropriate for reuse. The smaller you break down your content elements for reuse, the more complex it is to reuse and manage the content. If individual words are the only component of information that changes, consider using variables, which can have a different value depending upon the instance. Variables are much easier to manage than individual word-size elements. If sentence fragments can be reused, consider creating the reusable element at the sentence level and creating a derivative element by changing the portion of the sentence that is not appropriate for reuse.
To ensure that an element is reusable in many instances, you may contemplate writing very generic elements. The generic reusable element may serve the reuse requirement, but may compromise the usability and comprehensibility of the content. Never compromise the quality of the content to reuse it. Consider not reusing the content, or using derivative reuse so the content can be adapted to meet the needs of the specific reuse instance.
There may be times when you need to create unique "one-off" content or ad-hoc content to meet a specific need where existing content is not appropriate for reuse.
As you perform your analysis and build your models, consider the value of the reuse. Reuse content where appropriate and effective and always ensure that the reuse will not compromise the quality and usability of your materials or make the reusable content very difficult to create, find, and manage.