I earn my wages as a sound engineer. Granted, not the studio recordist one but maintaining studios and lecturing is a big part of my job. I also do record and mix post and am a freelance engineer.
Being able to understand wiring, components and some unit's signal flow allowed me to save many gigs in both live and studio - identifying dodgy channel strips to soldering a cable straight to a point in the unit we needed, down to improvising resistor serie networks to provide power to pedals.
Also, am building my own distortion pedal in my spare time.
Now, I do have these units in the bench. Maybe it is crossing the line into electronics but I honestly thing nothing bad can come from knowing a piece of gear inside out - I don't, but I'd sure love to know more and more about this stuff. Being able to mod pieces of gear or bring stuff back to life is a sweet skill to have.
I don't mind if this topic is closed due to be really outside audio bearings, and I do understand. It's maybe more towards recording "engineering" than recording arts and production.