Although CATT is meant for as a testing tools, many SAP users have now use CATT frequently to upload vendors master data and make changes to other master record.
SAP Consultant and Abapers tends to used it for creating test data.
With CATT, you don't have to create any ABAP upload programs and this save on development time. However, you still have to spend time on data mapping into the spreadsheet format.
The transactions run without user interaction. You can check system mesages and test database changes. All tests are logged.
What CATT does is record you performing the actual transaction once.
You then identify the fields that you wish to change in that view.
Then export this data to a spreadsheet to populate with the data required.
This is uploaded and executed saving you keying in the data manually.
To perform CATT, it has to be enabled in your production environment (your system administrator should be able to do this - SCC4).
You will also need access to your development system to create the CATT script.