drill angles are only irrelevant in symmetrical balls but remain relevant in asymmetrical balls.
This is correct.
Small drill angles place the MB of the ball near your VAL.
Ball motion or shape is moreso effected by the core of the ball. The Layout matches up the bowler to the ball, as the goal is for the ball to effectively go through all 3 phases of motion at the right time, to create the highest carry possible.
With the MB near/on the VAL, the axis migration happens earlier and sooner. The sooner the axis migrates across the Pin to Spin line (Pin to MB) the sooner the core revs up. By forcing this to occur as soon as possible you create a stronger and earlier hooking ball, which is rounder and more arc like motion, as it depletes energy sooner, resulting is less right to left movement when the ball encounters friction down lane.
The later this happen, (MB in the thumbhole appears to be max before experiencing diminishing returns IMO) the longer/sharper the reaction, because the axis migration
doesn't cross the pin to spin line until much later.
I'm not familiar with older layout terms, but if CG Axis is... what it sounds like (CG on your PAP?) then I would tell you that, CG doesn't matter, and it should have nothing to do with how you layout the ball.
Pick a Pin to Pap distance that matches your tilt so that your tilt burns at the proper rate.
Pick a VAL angle based on how quickly you want the ball to respond to friction.
Then pick a Drill angle based on how much length you want to see out of the first transition.
Bigger drill angles correlate to longer PAP to PSA distances in the Storm VLS system. (More length, more skid, more energy retention) They are accomplishing the same thing.