After more than four decades in business, there are certain things that Stan Richards, the 78-year-old founder of The Richards Group, believes to be true. Employees, for one, must arrive by 8:30 a.m. (not 8:30-ish-they have to punch in). Time spent on the job must be accounted for in 15-minute increments, daily. Fail to do so, and you'll be docked $8.63. Arrive promptly to meetings or be shut out of them. Close of business is 6 p.m. Finish your work and go home.

Given all that, you could be forgiven for concluding that Richards runs a widgetmaker or a call center or a print shop—the kind of operation in which work needs to be highly regimented to get done efficiently. In fact, The Richards Group is an advertising agency.

And not just any advertising agency. Founded in 1976, The Richards Group is the largest independently owned ad shop in the country, with billings of $1.28 billion, revenue of $170 million, and more than 650 employees. Its portfolio is packed with some of the most memorable campaigns of the past 30 years. Chick-fil-A's famous cows, those alluring Corona beer ads with couples lounging on the beach, Motel 6's "We'll Leave the Light on for You"… all were born at Richards's Dallas headquarters. Most recently, and infamously, the agency went perhaps a bit too far, sparking a nationwide controversy with a set of startlingly direct ads for Summer's Eve cleansing wash. The spots declared "Hail to the V"; some cheekily used hand puppets to play the roles of multiracial talking vaginas.

Highly structured and rules-bound companies, of course, are not supposed to produce work like this. "Creative" industries such as advertising, software design, and the like are supposed to require a loose, anything-goes culture, in which workers are free to come, go, and dress as they please. It's a world of verdant campuses, foosball tables, and caffeine-fueled all nighters. Introduce things such as start times, end times, and time sheets—rules—and watch your creatives run for the exits. Richards, obviously, feels differently. "We need to be disciplined," he explains. "We are not gallery painters who paint when the feeling moves us." And Richards has made it work. The 29 creative group heads at Richards's shop have an average tenure of 17 years. "The genius of the place is completely counterintuitive," says David Fowler, who wrote the landmark Motel 6 spots back in 1986 and today is the executive creative director at Ogilvy & Mather in New York City. "Somehow, Stan made you feel like you were only limited by the size of your ideas."

The way Richards sees it, his unusually regimented approach, honed over the course of decades, will outlast shifting tastes, disruptive technologies, and—with the help of a decidedly unconventional succession plan of his own devise -- his own mortality. Today, as he encounters obstacles he never could have predicted (such as bloggers enraged by his agency's take on feminine hygiene), he knows a good agency, like a good ad, binds commerce to art. He's betting his legacy that his rules will remain the linchpin.