I think it really depends on your itinerary. 15 days is a short time to visit Europe. Maybe it could make sense if you plan on visiting only one or two countrie

I think it really depends on your itinerary. 15 days is a short time to visit Europe. Maybe it could make sense if you plan on visiting only one or two countries and smaller cities. But if you want to see let say, Paris, Roma and Berlin. I don't think it's a good option.