If you are assuming a 25 - 35 year old, you must be very risk averse as 30% is pretty high for such a young person to have in bonds.
Of course, 50% bonds was easy to recommend 40 years ago when US savings bonds paid 5-7% annual interest, guaranteed for 30 years.
Inflation in 1980 was over 13%. 2015 was less than four fifths of one percent. Bonds today pay out much better than they did 40 years ago.