Um...not always. When Apple had their first, waiting-in-line hit with the iPodin particular the first wave of smaller, colored iPods...well, let's just say I'm old enough to remember all kinds of mistakes and miscalculations. And anxious and unhappy customers. And what about the fiasco of the "white" iPhones? Waiting an extra week or two for your watch is nothing compared to those who waited for that first white iPhone.
Thing is, what you're talking about with current launches like the recent iPhone 6 going so smoothlyand/or recovering so quick from launch snafus--is all due to years of practice and learning from early mishaps. Apple didn't get that smooth at launches by way of magic or by just "knowing" how to do it. The company and its stores had to learn and often learned the hard way.
Now, with the watches, they're trying something different. If may look like a small difference to you, but however large or small, that difference can throw a company off it's game. It's not exactly like what they're used to. I imagine that they're probably scrambling right now to fix whatever gummed up the works and is keeping so many watches from getting to their owners. They know we all wanted them on that first day. But, however much they may have calculated for everything, they obviously didn't.
Still, I don't think we're going to have to wait as long as fans did for the white iPhone (I sure hope not!). So...maybe not a failure of a launch just yet.