Converting Training

I've heard many people say the best way to gain stats is to feed hay cubes until age 3 and then convert disciplines. What is the point of this? Can someone please explain the whole process?

I could be wrong because I don't treat with hay cubes but I think the general consensus is this:

Hay cubes gives random stats in every stat area, so when you convert to training all of the stat areas split into the two areas that the discipline consists of I,e(racing is speed and endurance). So I think by doing this you get more stats for the two areas after you convert.

Apologies if this makes no sense I'm not good at explaining.