It's all about the process.
Develop a process, test and refine it until it is a winning formula for sales, then repeat as required. It's a simple system and one that we all forget about.
How many times have you come up with a marketing or sales promotion and only done it once? If you can measure your return on investment and it is sufficiently higher than the cost, why don't you keep doing it. Mostly we tend to think that we have done that once and we need to do something different next time, but in fact, repeating and refining the process can be vastly more successful than starting over each time.