Not sure where I picked it up but honestly smacking the plunger is my preferred shot. Take #addams-family for instance if you do it right its a huge advantage at least for me I can lock shots all day using the smack plunge. Another one is #white-water , I can hit my smack plunge better than a normal one to start the ball.
Other times I use it to the get energy of the ball in play up, for instance for those times on machines where you ball just can't quite make it up the ramp. Power plunge it hit your shot and it goes right up the ramp no problem. But I pick and choose which machines I do it on. If its useless then yeah I'll just flip it out like normal. For the 1st shot it definitely can change you game up, I love using it for superskill shots, #deadpool-premium is one of them.
Occasionally though I will have the problem of the ball leaving the play field. I've knocked one of the small spaceships off of its roost before in #attack-from-mars and taken off the wing of the Tie Fighter on #star-wars-stern-le . Although I don't attribute that to the smack plunge its just I am too used to playing on the fly and my ball energy stays up and it does things that balls probably just shouldn't do. I'd honestly like to become more of a finesse player but its just my go to I guess.
Biggest problem that I have is that the ball getting english on it just like in pool. If you've played pool the ball actually curves. An example of this is on #metallica if I even touch the captive ball and have my energy built up it goes directly in the snakes mouth, literally no questions asked. On the flip side though I've tried to do a dead flip and take some energy out of my ball, it hits the flippers goes up and literally stops dead and drains down the center. Very frustrating indeed, I'd actually love a ball that has something on it, a stripe or a dot, to tell what kind of english I have on the ball.
I dunno I guess I'm still learning but to read comments in here about calling out people for looking like douche for that shot seems pretty judgmental. There are definitely reasons to smack/power plunge.