As it turns out, it's perfectly legit to get same abilities on a piece of gear from Splatnet.
I just got the Rockenberg shirt with Run Speed Up.
Now the drinks are even more useful now.
Say drinks effect is 25% additive (because my small sample size test 9/32 shows the percentage to roll the desired ability on an unfavored gear is 28%, and without the drinks the percentage should have been 5.7%), combine with 28.5% chance of rolling Run Speed on Rockenberg gear. The chance of rolling Run Speed on one slot is now 53.5%.
(53.5*53.5*53.5)/10,000=15.31%
So this means there are 15.3% chance for you to "level up" your gear to have all 3 same abilities.
Much better chance than using Super Sea Snail, you need to scrub and level up.
Take half way point into mind:
If you are a lucky person in real life, then you would need to scrub 4 times to get a perfect roll.
If you are unlucky in real life, then you would need to scrub 8 times to get a perfect roll.
TL;DR
Favored Brand with Drinks: 15.3% chance to "level up" a perfect gear (4 same abilities)
Favored Brand with Snails: 2.3% chance to "roll" a perfect gear (4 same abilities)
So, use all your Snails to gather ability chunks first just in case you rolled 2 or 3 of a kind. Then scrub and use drinks.