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Perhaps the most problematic visibility aspect of this design is the location of the add buttons on the main page. The bottom of the page is not necessarily the first thing that will capture the user's attention. The design is so simple, however, that this is unlikely to represent any substantial difficulty.
Efficiency
This design is efficient through redundancy. For instance, it is possible to add a document at both appropriate places - the main page and the "edit company" pages. The link to the main page on all pages but the main page means that one is never more than a click away from the main page, and two clicks away from the task list.
One area where efficiency is potentially low, however, is that the state of the system is not very visible once one is within the add document page. A user might forget the names of all her documents and accidentally try to give one of her documents a name she has already used.