EGR Chart, page-15

I think the amount of the different exchanges is a historic reason, when there has been no computers and floor trading was done many cities had their own exchange.

Now today you have different exchanges with different opening hours and different trading costs. So you can chose freely wherever you want to buy or sell your shares.

That it’s why it is No accumulated view and if you want the VWAP and total amount of shares traded you have to add up.
But care Stuttgart exchange is not shown on Ariva.de. We sometimes see some trades there.
I might just open a thread where I post each day the VWAP and volumes for Germany before you start trading to make things easier.