A recent study from three economists from the Federal Reserve Bank of Chicago confirmed that momentum investing can be a winning investment strategy, even when you account for the risk of periodic crashes. But in a piece for The Wall Street Journal, Robert Litan says that doesn’t mean investors should go all-in on momentum approaches.

“Even with low brokerage commissions, the trading costs would eat away any superior returns,” writes Litan, a senior fellow at the Brookings Institute. “In addition, many investors don’t have stomach to bear the costs of those crashes.”

Litan’s advice: “Stick to the standard advice: Don’t try to time the market. If you have cash to invest, do it gradually and consistently (the ‘dollar cost’ average way to invest), adjust your mix of stocks and bonds to your age (the older you are, the less of the former and more of the latter), and put your stock money in index funds.”

“It’s hard to do,” he adds, “but it’s best to sit back and not let emotional reactions to daily news tempt you to move your money around too much.”