Drupal 7 fields are great, but using multiple valued fields and field collection you can quickly reach the point of having a form that looks like this:
In this contrived example I've got two field collections and a multi-valued 'Links' field within that.
Although it's reasonably clear what clicking 'Add another item' will do in each case, when the form is full of data it can become less so.
We can give content editors a helping hand by changing the buttons from 'Add another item', to something more useful like 'Add another carousel item' etc. With the Custom add another module we can do just that. We can make that form look like this:
Now it's much clearer what clicking on one of those buttons will do.