I have had more luck with the ability drinks on gear without the right brand, I got the Mask and Shoes pure without spending any ability chunks on them, while I got x2
subs and x1 random sub on my jacket which I had to spend x30
chunks on to make it pure and none of these gear pieces has Rockenberg as brand which boost the chance of getting
subs.
I have had great success with farming ability chunks in Salmon Run since I enjoy it, so I can easily farm duplicate gear all the way to 10.000+ reward points and while the chunks are random and luck based to get on the duplicate gear you're gaining both cash and chunks compared to scrubbing gear which cost cash, but scrubbing is less random since the brands help more at farming the chunk type you want.
these are the odds for sub abilities on Grizzo Gear:
50% for 0 subs, but you can trade in the duplicate for cash.
40% for 1 sub which you can trade in for 1 chunk.
10% for 3 subs which you can trade in for 3 chucks.
once you reach high enough Profreshional you will be able to get 200+ reward points every run meaning you will get either cash or chunks every run which is pretty fast with the fact you're not spending any cash on scrubbing.