You know Mark, I agree with your comment that the answer is "both." I work for a "hare" division in a mega sized company, and as a result, I tend to engage in both strategies simultaneously. I think the secret is to build your regulatory strategy within the context of your overall business goals. In other words, at the end of the day, the key question is "what business do you want to be in?" If the goal is to build a company that will last into perpetuity and you have the funding to support a long range vision, the tortoise method may be more appropriate. If, on the other hand, you are in the "start up" business or division and plan to hold on to the company or product only long enough to make it really attractive to a suitor, then finding the low hanging fruit that gives you the widest market exposure and deepest penetration is where you want to be.
A word of caution from lessons learned the hard way. Don't get lost in your enthusiasm for your product or dream. Things don't always go the way we think they will. So, even when we're in a hare mode, I believe it's important to have a well-conceived longer range strategy that allows you to incrementally add functionalities and indications, expand a research or clinical scope, or make an effective and fairly quick strategic shift. Building a comprehensive "program" that supports the cash flow needs of the business while buying you the time to weather the regulatory challenges that can arise is extremely important ... no matter what kind of business you're in.