P.S. As you increase your training level, you either unlock new drills or improve efficiency of existing ones. I have a few drills where I am on the second level (of three), which makes them 10% more efficient. I assume the third level will make them 20% more efficient.

If you train your players using 2nd level drills, your math will change to

228 green packs for a new role, 182 or 228 for an SA.

And using 3rd level drills, if I am correct about the 20% efficiency bonus,

209 green packs for a new role, 167 or 209 for an SA.