public void Foo(Fizz f, Buzz b) {
  if (null==f) throw new ArgumentNullException("f");
  if (null==b) throw new ArgumentNullException("b");

  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
}

// vs

public void Foo(Fizz f, Buzz b) {
  if (null==f) throw new ArgumentNullException("f");
  if (null==b) throw new ArgumentNullException("b");
  FooDo(f, b);
}

private void FooDo(Fizz f, Buzz b) {
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
  // Do stuff with f and b
}