Portfolio design comes in many flavors, but so do investors. Finding a sensible balance is job one in the pursuit of prudent financial advice. Yet for some folks the idea of keeping an open mind for customizing strategy to match an investor’s goals, risk tolerance and other factors reeks of treachery. There can only be one solution for everyone—all else is deceit. Or so some would have you believe. This biased worldview comes up a lot with the discussion of buy and hold, but the one-size-fits-all argument knows no bounds.

The danger is that pre-emptively deciding how to manage assets for all investors is the equivalent of diagnosing illness and recommending treatment before meeting with the patient. Sound financial advice requires more nuance, of course, for two primary reasons: the future’s uncertain and the human species is afflicted with behavioral biases.

In other words, a given investment strategy can be appropriate–or not–for different individuals. Consider the concept of buy and hold. By some accounts, it’s all you need to know. Stick your money in, say, the stock market and let the magic of time do the heavy lifting. Sensible? Perhaps. But it may be hazardous. The determining factor is the particulars of the investor for whom the advice is dispensed.

Buy and hold—perhaps by focusing heavily if not exclusively on stocks via a handful of equity funds—may be eminently appropriate for a 25-year-old with a budding career, a saver’s mentality, and the behavioral discipline to focus on the long-run future. The same solution can be toxic, however for anyone with a time horizon of 10 years or less. Even for someone who’ll be investing for much longer may run into trouble with buy and hold if he has a tendency to over-react to short-term events. In that case, buy and hold can be wildly inappropriate for an investor without the discipline to look through market crashes and bear markets.

Ah, but that’s where a good financial advisor can help by keeping the client on the straight and narrow: Ignore the short-term volatility and stay focused on the long term. Fair enough, but it doesn’t always work. Some investors will bail at exactly the wrong time no matter how much hand-holding they receive. Deciding who’s vulnerable on that score can be tricky, but not impossible. Perhaps, then, a portfolio strategy with less risk—asset allocation—or the capacity to de-risk at times–some form of tactical–is more appropriate for certain individuals.

The flip side of this equation is no less relevant. Forcing every client into a tactical asset allocation strategy simply because that’s your specialty (and/or it pays better for the advisor) is also misguided. Higher trading costs, taxable consequences and the inevitability of timing mistakes can and probably will take a bit out of total return over the long haul relative to buy and hold. The “price” of tactical can still be worthwhile for some folks if the portfolio has a tamer risk profile.

The point is that there’s no way to decide what’s appropriate without first understanding the client. Granted, a 25-year-old investor is more likely to benefit from buy and hold vs. a newly retired 65-year-old client. But there are exceptions and it’s essential to identify where those exceptions arise.

The good news is that there’s an appropriate strategy for every client. The great strides in financial research and portfolio design capabilities via computers over the last several decades provides the raw material for building and maintaining portfolios that are suitable for any given client. Buy and hold may still be appropriate, but maybe not.

The greatest strategy in the world is worthless if a client jump ships mid-way through the process. As such, the goal for managing money on behalf of individuals isn’t about identifying the strategy with the highest expected return or even the strongest risk-adjusted performance. Rather, the objective is to build a portfolio that’s likely to work for the client. That may or may not lead to a buy-and-hold strategy—or some variation thereof. Such talk is heresy in some corners. But matching portfolio design and management particulars to each client’s time horizon, goals, etc.–and behavioral traits—is the worst way to manage money… except when compared with the alternatives.