score:-1
As long as you leave the Schengen area at the end of your trip, I don't think anyone will care what you do.
Upvote:5
I mostly agree with the answer by Henrik, but consider this:
From that follows a third point:
Going directly home, instead of the planned last leg of the journey, would be no problem at all.
Traveling through a different, unplanned Schengen state on your way to or from the main destination is not a problem as long as it sounds plausible. For instance, if you had planned to enter France and then go to Germany for a conference, and then get a better flight through the Netherlands, you can skip France and enter through the Netherlands instead.
Coming and leaving a week later than planned should be no problem, if the visa had enough validity. Business meetings and vacations get re-scheduled all the time.
But almost doubling the planned duration (17 days to 30 days) looks bad.