Actually the new bodybuilder, will gain muscle and strength at a much higher rate, than any experienced bodybuilder. Even if (when) the weight used, is much lower.
The reason for this is: What makes the muscle grow, is to what degree you can overloaded it, in comparison to its conditioning.
Over time, a muscle will become more and more conditioned and while this is, to some degree, reversable (using SD) it will accumulate. At the same time, increases in strenght, will be so much harder to achieve. Thus leaving less potential for sufficent overload.
To sum up. Once you have adapted (at a neural level) to the exercises you have chosen, this will most likely be when you'll be getting your best gains, ever.. Regardless of the weights you are using.