The facts that are indisputable are that we are living longer and returns from income generating securities such as bonds have fallen to historic lows. This results in an increased focus on making retirement portfolios more efficient at generating income. Retirees must grapple with two uncertainties: future market returns and how long they will live.

Remove these uncertainties and it would be straightforward to project a future consumption pattern that uses all the retirement savings while they are alive. We would consider this an efficient depletion strategy.