To some extent, I disagree. I do quick calculations on simple circuits like musical, "stomp box" circuits, like finding the frequency range allowed by the coupling capacitors. I do a little bit of math to discover whether an air conditioner has the right difference in air temperature (BTU = 1.05 CFM dT). When I'm tracking down milliamps in a precision analog circuit, math is often the key to finding the problem. That isn't, "more math" compared to the original design work, and I'm not talking about my tube jockey days, but a quick calculation here and there is a method I use constantly when troubleshooting.Really,in vacuum tubes, there does seem to be some magic happening. And somebody has to be able to recognize symptoms and change the right part without having to test each component. The math is the foundation for the insight for design, but once a thing is designed it still needs to be made to work. And at that point more math is seldom the solution.