I think its a bit interesting that a 18 y/o Fast-trainer as a 7 star has the same TEF as a 20 y/o Fast-trainer. I expected the TEF to drop more with age, but it seems to stay the same until at least 21 y/o. But I will check this next season. Maybe it even stays the same until 22 y/o?
18-21 y.o. have the same gaining
After that, it drops