Why in god's name would you sentence someone to 400 years in prison unless you believe in Highlanders?
Here in Norway, the maximum sentence is 21 years, and doesn't stack beyond 21 years.
First-degree murder has a maximum of 21 years. So, you could have two guys in jail, both serving 21 years, one which murdered one person, the other which murdered say 69.
Now, I believe that taking 69 lives in cold blood is significantly worse than "just" one. However the sentence does not reflect this.
So while 400 years for one murder is a bit much, sentencing the second guy to 69 * 21 = 1449 years in prison would at least more accurately reflect the crime he committed.
How many of those years he must serve could be orthogonal, if society wants it that way.