You’ll find when you get into industry that a big chunk of the theoretical side is discarded and most of the job runs on intuition and knowing the gotchas and gluing bits of data sheets together then writing software. That’s what the book covers.

Occasionally you’ll need to dig deep into it and particularly if you do RF stuff but that’s about it.

I was disappointed for about six months when I landed my first position at a defence contractor when I found out their senior analogue design engineer had a circuit crib book and most of the designs were sourced or bodged from that and then adjusted on a breadboard. I was simply amazed at how informal it was. The stuff worked, was in budget and performed well. Surprisingly mathematical and theoretical knowledge was rarely discussed.

The signal processing and software guys did all the legwork really.

Me, I ended up writing engineer ERP systems to replace paper and then jumped into the software market.

Now I play around with things and I’ve built a lot of stuff without even firing up a calculator or thinking about the theoretical side of things. Everything has a computer in the middle with a little bit of analogue stuff around the edge which you can usually just pick out of the book.

Edit: to be clear I know Laplace, Nyquist, how to do FFT/DFT, network theorems etc but I just don’t need them most of the time.