We would prefer that you always use most current version of an upload spreadsheet.
From time to time, we make adjustments to the templates themselves based on customer feedback or technical enhancements. Sometimes these changes are subtle and you may not be able to notice them easily. Therefore, you cannot always rely on a saved copy that you fill in each time.
Best practice: always generate a NEW spreadsheet template, filling it in and uploading it as soon as possible.
Please note that the template to add new properties is in a separate location from those which make modifications to currently existing properties.