Repeat is for filling out mock-ups, making it easy to duplicate blocks of sample content.
Ok, but why?
The main use is duplicating sample content in templates, examples, prototypes and demo pages but without needing a server or maintaining a mess of copy-pasted HTML.
Other uses include mocking UI actions that add content, such as dummying pagination or faking infinite loading content.
It's simple but I do this so often when prototyping front-ends, I wrapped it in a single function.
$(<selector>).repeat(n [, target, deepClone])
n is the number of times to repeat the selection
target (optional) where to append the clones, otherwise appends to parents
deepClone (optional) whether to perform a deep clone, default is false
Every selected element is then cloned
n times and inserted into to their respective parent(s) after the last element in the selection, or
target if specified
Returns: the newly generated clones (in case you need to bind them or something)
You can seen an example and get the code over at GitHub.