Or, rather, despite her very unusual "success" it had to build up to unavoidable evidence that couldn't be ignored or explained away. There is no way police supervisors can claim with a straight face they are only looking out for public safety with that much evidence the public is in danger of false arrest.
I mean really. How much thinking does it take to ask oneself, "Hmmmm. That's pretty coincidental. The most drunks are out driving at exactly the same time Trooper Steed is working. The drunks even shift their patterns around to coincide with her work hours. Hmmmmm."
And, this is from the same industry that will use just about anything it can to justify being suspicious for a car search, dog sniff, or detention. Meaning, they'll latch on to the tiniest thing and claim in court it justified a suspicion.