oh, so you mean the +1% you gain is not consistent, sometime got big, sometime none, and sometime got big again

that's normal,

let say to master the shooting technique, maybe for example you need at least 3 shooting training session to gain +1% of shooting skill.

or maybe 4 or 5 session, or maybe just 2 shooting session.

even in real situation, you don't know the exact number of training session you need for yourself to master that shooting technique