It was a nice idea to break it down my friend but there are a few key points I would like to touch on!
1. " needs to gain an average of 2.68 skill points per day" , that is just not going to happen!
2. Rather than look so deep into it, it is far quicker to just look for age and value as this is a easier base line for finding quality players!( no guarrantees but alot of the time), if you compare 18/19y olds of the same quality by the price this will give you a prety good idea which is the better player! e.g 18y Q 68 21M & 18y 69 24M I would say the latter is going to be a faster trainer.