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.