Honest question: what kind of rigor and abstraction can help us apply maths to solve problems? Don't get me wrong: I enjoy studying abstract maths and was pretty good at it in school. It's just that when it comes to what to study to make one a more effective problem solver in engineering, I was wonder I can best allocate time. For instance, I find studying probability models more helpful than studying the measure theory when it comes to applied data science or statistics. I also find studying books like Mathematical Methods for Physics and Engineering, which focuses a lot more on intuition and applications than rigor, is more effective for me than going pure math books.