MRB,
I haven't seen the Hewitt study so I can't comment on it. If it takes the conventional route and measures retirement adequacy by assuming that you need 70 to 85 percent of your pre-retirement income to maintain your standard of living in retirement, it suffers from the fundamental flaw of most financial planning:
YOUR PRE-RETIREMENT STANDARD OF LIVING IS NOT THE STANDARD OF LIVING YOU HAD MOST OF YOUR ADULT LIFE.
The conventions of planning ignore certain major life realities such as procreation and the resulting support of children or the existence of debt service. Both reduce the portion of our income that is available to support consumption throughout most of our adult lives. As a consequence, the amount of money we need to save is lower than commonly estimated.
This doesn't mean that EVERYONE is oversaving. Millions of Americans are clueless, driving toward a cliff because they save little or nothing and blow the major opportunity for saving when the children are on their own by upgrading their spending.
But most of the people who visit financial planners are probably aware enough that their savings will be sufficient or in excess of what they need to maintain their adult standard of living when they retire.
Here, for instance, is a recent column about how it works out for a household with a single earner with a $100,000 income. That's the top of the Social Security wage base which means that 94 percent of all earners have that income or less. While a single earner isn't the same as a dual earner, it's safe to say that the vast majority of households in America are in a similar position.
http://assetbuilder.com/blogs/scott_burns/archive/2008/06/06/the-n-factor-and-retirement-planning.aspx
Scott