Having almost finished an honours calculus sequence, I'm now about to enroll in a real analysis course. I've been buying some interesting books lately on top of my required reading list (for example, I supplemented my Calculus book, which was Peter Lax' "Calculus With Applications", with Mercer's "More Calculus of a Single Variable"), and I'm now faced with the opportunity to buy a book on various Calculus techniques and tricks - Klambauer's "Aspects of Calculus", to be precise - but I'm not sure if working through this book will be worth my time, or if I'd be better served spending my spare time working through some other topic.
So, in trying to find an answer to this question, I think it's fair to generalize it and ask instead, how important are "advanced" differentiation and integration techniques and tricks to a mathematics major intending to work towards a PhD in mathematics - possibly aspiring to work in academia? I'd imagine such a question leads to different answers depending on what area of mathematics you decide to work in, so I'll leave the area unspecified.
Also, I'm aware this question is somewhat similar to this one, but I'm specifically asking about the advanced techniques and tricks as discussed in Klambauer's book, not so much about calculus in general. Klambauer's book is quite particular about what it covers (difficult rational integration examples, hard derivatives, complicated series etc etc).
Edit: again, allow me to emphasize that the answers will depend on what area of mathematics one decides to work in. I'm aware of that, and I knowingly and purposefully left the mathematical area unspecified so as to encourage open-ended answers that will end up painting a more complete picture than only focusing on the relevance of advanced differentiation tricks and techniques in just algebraic geometry, for example.