A popular five book right now has a lot of good information in it, but some things that are just kind of made up for the current times. Yield shields and cash cushions are two of those things. That does not mean that what they recommend in that book doesn't work. It works because they generally have a diversified 60-40 portfolio.That is the only reason that works. In fact, those ideas are window dressing that will actually detract from the performance of a portfolio.