I reply with a own quote I wrote in 2016 #11
"Train a SA is basically a impact of adding a +1* in some skills, basically internally, and like unlock a manner to play but sometimes the impact is not perceptible because I guess the base of effectiveness or contribution of a player is so low..."
https://forum.topeleven.com/top-elev...ability-2.html
Yes, it's something known that it adds a star, but to few selected attributes, linked with the SA.