I dunno, I think the number will increase above dozens. They certainly won't start out doing dozens a year, then pare it down to one or two, and eventually realize the don't even really need it. More likely, the number of uses per year will creep up, until eventually it's not as controversial as it used to be, at which point it'll jump dramatically. As a comparison, in the U.S., no-knock warrants were controversial when they were first implemented, and they were stated as being only for very special circumstances—ya know, terrorists and such—and now they happen about 70,000 times a year, mostly for dangerous activities like marijuana possession or distribution. The ratchet only goes one way, which is why it's dangerous to grant the premise of "we'll only use this in exigent circumstances, we pinky swear".
I've seen people literally smoking joints in front of the police station.
Listening in on someone to find evidence of them doing something illegal is actual work, the odds of them doing it to everyone are rather low, I think they'd rather go watch a football game or something.
