Munich-Innsbruck-Venice-Barcelona Trip - Too much?

I am planning a trip for 4 of us, and this is the current itinerary. Is this too much?

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9/6 - Chicago, IL, US to Munich, Germany

9/7 - 9/10 Munich, Germany

9/10 Munich, Germany to Innsbruck, Austria

9/10 - 9/12 Innsbruck, Austria

9/12 Innsbruck, Austria to Venice, Italy

9/12 - 9/15 Venice, Italy

9/15 Venice, Italy to Barcelona, Spain

9/15 - 9/17 Barcelona, Spain to Chicago, IL, US

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I am worried it feels rushed but I am not sure!