It's that time of year when chain restaurants report their year-end earnings and industry rags scramble to report and explain all that went right and wrong for the industry over the past 12 months. People in boardrooms ponder these lessons, and sit around trying to think up ways to gain our business in the coming year. It's easy to be smug at this time of year, to sit back and think, "yeah, no shit that dumb promotion of yours didn't work." But it's also a little depressing -- who would have thought a Dorito shell could be such a lifesaver for Taco Bell? So here are the 5 lessons learned from 2012's chain restaurant successes and failures.