Speed and earnedness are inversely correlated. The faster you have to produce something, the more you have to employ, as elements of the thing, what others have already made.
Deservedness is less about 'how much ' and more about 'when', and 'before whom' or 'after whom'. Deservedness determines seniority and duration.
In sum, fairness determines how much and who, while deservedness determines when and in what order.