Simultaneous Update

Never ever ever ever ever ever ever ever ever ever use Shared Workbooks. Unless your life is boring and needs livening up.

Thats what i thought. If they dont know Access, they will have to choose other options....not provided by Office.

In many cases this will do in Excel:

If all users can only open a copy of a central workbook : Worbooks.add "\\central.xls"

You only have to provide for a small macro to save the modifications made by each user in the copyfile into the common workbook "\\central.xls"
The opening of the common file, the adaptation with the modifications and the saving of the common file will only last milliseconds if performed by a macro.
The chance of multiuser interference will be minimal.

Especially if you allow users only to use userforms to change anything you can have a very standardized structure of the data in Excel.
Everyone who has read-only access to the common file will also only be provided with a copy of it.

There are a lot of organizations that have no trillion employees working with the same data simultaneously.