It's just like what I say about calculus: it's important to understand the basic concepts of integration and differentiation but you are NEVER going to solve integral or differential equations in real life

Actually I have solved differential equations to replace code that was using numerial methods to calculate some stuff. Tee end result was code that ran a lot faster and gave a much more precise solution. It took a couple of pages of maths, and because I am not very good at maths it took me a while, but it was worth the effort.

I have also had to use the good old quadratic equation to solve equatiosn that were calculating acceleration or deceleration, and plugged in the resulting formulas to replace code that was using numerical routines to solve these as part of a robot path planner. In the original code the previous guy had at least left clear comments saying what the code was trying to achieve, and a note in the comments to say something along the lines of plugging in a better solution at some point in the future

This highlights both the advantage of good commenting practice, which made it easy for later programmers to see where improvements could be made, and the importance of being able to apply this kind of maths to problems instead of just going to the numerical toolbox.