Just my two cents on this.
Michael Porter's Competitive Strategy is a good textbook (still very valuable today) for MBAs or for your general interest / knowledge.
I think you can gain much more in terms of the ratio effectiveness / time by using other sources, specifically thought to prepare you for the interviews
I will cite the obvious, from my point of view
1) Mark Cosentino - Case in Point
2) Victor Cheng - Case Interview Secrets
3) US MBA Casebooks, in particular - Wharton CaseBook - they have mock cases solved and a general introduction "101" part to really give you the basics about a consulting interview - very helpful in my opinion
4) Victor Cheng - Look over my shoulders (recording) - these are very advanced, in my opinion and only useful as a "polishing/finishing" tool once you are proficient
5) PrepLounge resources online - very to-the-point and helpful
Hope this helps,
feel free to shoot me a message, should you want to go deeper in the topic.