Since you want each flow to start on a new page, another way would be not to use flow headings at all.
Start every flow with the “first” layout and edit it to display the flow title and no page numbers.
Then create a different layout for page 1 of the score which also displays the title of the piece.
That way, you only need one page override on page 1, and that won’t give you any problems if the number of pages in a flow changes when you edit something.