We can check my math together.
A green pack gives 15% condition.
A drill (any drill*) gives 1 1/3 training point towards a skill, SA or role for each 1% of condition spent. So a "Hard" drill will give 4 training points at the cost of 3% condition.
By this formula, one green pack (15%) buys you 20 training points**. 100 training points gets you one point closer to an SA or a new role. So for 5 green packs per player you should expect to see a progress of one point (out 40 or 50 required). If you spent 10 green packs between 3 players, it is likely that all three are close to getting their first point, but are not there yet.
Without power training (farming or buying green packs by the hundreds) you can expect to train a new role or SA over the course of the season, give or take. And that's if you have a reasonably fast trainer. I have stopped bothering. I only train SA or secondary position to prevent the player from gaining the next star. Other that that, it's more efficient to buy them with the desired extra roles and SAs.
The formula that I just now came up with as I was thinking outloud seems to be:
250 green packs for a new role, 200 or 250 for an SA.
Does this seem right to anyone and has it changed from the previous version?
*some say only Attack and Defence drills contribute to SA and roles, not T&M; what I mean is that all drills have the same training points to condition burn ratio.
**this is on average; the actually gain will depend both on the player's trainability -- younger players are more trainable, but not all are created equal -- and on a small random variation just to make it interesting