A good coach will be good for about a decade, give or take, and then the law of diminishing returns tends to kick in. There is too much work, too much pressure, too much of everything to be otherwise. And, a lot of coaches tend not to evolve with the game. They want to stick with what they've done to be successful, and so don't much like change. If you have a crack staff, and/or play in a weak conference as B.Bowden did with the fla. state in the ACC, you can have success for a longer period of time, but it's hard. Fulmer burned out, big-time--but he also let his staff get stale, and then chose the wrong guy to be offensive coordinator, which really was the beginning of the end. You need to recruit well and you need to have really good coordinators: Two requisites for success.