You should coordinate it with your other retirement savings, target asset allocation and tax efficient placement.
For example, my overall AA is 60/40 but for tax efficiency reasons my 401k is more than 40% fixed income since I own tax efficient equities in my taxable accounts.
While AA depends on your risk appetite, most ERs are between 30/70 or 70/30.
If something cannot endure laughter.... it cannot endure.
Patience is the art of concealing your impatience.
Slow and steady wins the race.
Retired Jan 2012 at age 56...target 65/35/0 AA