Calculo/Ventolin, don't put in the same pot runners of 800m and Marathon : the requirements for the events are very much different.
And, also, don't put in the same pot training in US (or Europe) and Africa, where all the athletes run a lot of km on hilly courses, that have the effect to improve the strength (specifically the strength endurance) more than using some specific session of weight lifting in a gym (something athletes have to do if their training is Always in flat areas).
If we find athletes with so wonderful natural technical action, such as Vivian Cheruiyot or Mary Keitany, who have the quality to use little fuel at the speed of long distances, and are 37 kg heavy, to use weights can only destroy the perfect balance (natural for them) they have between the speed, the specific endurance and the consumption of fuel.
Put in your mind that coaching is not something you can do with a calculator, but is to find different solution, on individual basis, for every athlete, looking at their morphology, their attitudes and the enviroment of their training.
You can find good "theorical" basis for your calculator, but can't consider all the factors out of your control.
Coaching an African athlete means to manage continuous emergencies, since a lot of factors are out of control.
Coaching is not a science, is an art.