That works well in theory, but reality doesn't work out so nice. People's needs for life insurance don't go down a whole lot, but they do change. What was once to support your wife and young kids while she got her career going, would instead help an older version of your wife pay for the hospital bills that led up to your death and to cover the shortcomings in your retirement savings. Another thing to consider is inflation. If your benefit amount stays stagnant over the life of the policy, then as inflation goes along, the value of that policy will go down.

I have a $1 million policy for 20 years. If I die in 2035, that's the equivalent of $550,000 in 2015 dollars.

I agree with Indy that you should find a good advisor that will look at all those variables with you. Don't go with one that gives you an amount that he pulled from thin air.