Question about team bonuses training

Quick question that I don't really understand about training the team bonuses. Why the Attack/Condition ones grow slower than Defence/Possesion (in my case)? My training situation:
- Drills: 2x Skill Drill, 2x Video, 2x Warm Up - So here everything is leveled
- Training with all 28 players - Alright... Condition should be growing fast!!
- From the 28 players (if my notes are correct: considering Defense (GK, DL, DC, DR, DMC) Possession (DMC, ML/MC/MR, AML/AMC/AMR) Attack (ML/MC/MR, AML/AMC/AMR, ST), I have 21 for Attack, 16 for Defence and 22 for Posession.

And with that... Defence (the one with less players!) and Posession grows about 50% of the circle. Condition grows something like... 35-40%. Attack barely does 1/4 of the circle.

Why?!

I think it based on the type of attributes you gain when you train. That's why when you use Pass, Go and Shoot the attack bar increase at a much quicker rate.

Even after saying this I do feel that attack bar grows at a much slower rate than other

Make bravery and heading a part of your attackers routine. Increases the chance to defend corners and sharpens your counterattack.