nope, a 3* fast trainner can easily reach 5 * at the end of season. let us count
75 sKP = 2.68 SKP a day * 28 day = 6.6 % skill per % condition = 1 skp/ 1 green
even medium fast trainer can do this easily when they 3*
you miss 2 points:
1) even a 3*stars fast trainer max can reach is 90skp in a season.
2) no reason to train him, because in our server you can easily get 5*stars for 1-2T each