[diracs_stache]

Control theory doesn't come up much in what I do but as a practitioner are Root Locus ever utilized? I've been unpleasantly surprised to see that exact positive feedback instance existing in places you wouldn't want (things wobbling above earth after a control input). Poles and Zeros felt like a lot of magic until a foray into complex analysis ripped that band aid off ;)

[Espressosaurus]

Oh yeah, it comes up. It's a way to check for stability and visualize the system. Phase and gain margin have come up more frequently for me, but a lot is going to depend on what you find the most natural way of attacking the problem to be.