When you save a file as an Excel Workbook (*.xlsx;*.xls), there is a checkbox at the bottom that says "Open the file after saving". Is there a way to set this to unchecked in preferences?
I don't think there is one specific to excel and I don't know where it is in the Preferences UI, but I think this running this will do the trick:
Set Preferences( Open the file after export( 0 ) );
Wow so simple. Works like a charm - thanks @ih !