In addition to using the Search option when trying to find a document within a group, you also have the ability to sort and filter the document display itself.
You can sort the columns by selecting the column header, such as Name, Date, Submitter, etc. Sorting by the Date column in descending order will always show you the most recent documents that have been added to the group.
On the left hand side of your screen, you also have a Filter option, which can provide you with just a select set of documents to review. The Filter option allows you to Search by Name, as well as filter by States, Submitters, and By Date.
With these options, you should be able to narrow down your document results list -- even if you don't know the exact name of the document you are wanting to review!