Thread:Myskaros/@comment-5950732-20140411140257/@comment-556400-20140411160948

It's different based on the spirit's current stats. If your spirit has high ATK and low SPD, it will get more ATK bonus than SPD for every merge; low ATK high SPD, the reverse. And the more stats the spirit has period, the more bonus points it gets, so, in theory, the later you go for bonus points the fewer feeds you need to do.