So I assume that when people in this thread say a pop in 9 weeks, the player already had some sublevel before start training.
Maybe closer to 1 pop each season for 27yo capped players, and one third of the normal speed.
Does one third sound as a better guess?
Unless the player popped in that skill, received training in it continuously the next 9 weeks and popped again, I'd be wary of counting that as the 'true' training time. He could have received some sublevel from cross-training in any previous week. Plus, of course, there's the elastic effect as well, that can throw the times off.