Elements of statistical learning vs introduction to statistical learning

Does anyone here work in a role where the theory in the former book is actually *needed* for their job? I finished the ISL book in my undergrad and picked up ESL at one point during grad school and the theory is quite fascinating. I know it’s probably not gonna be useful to me since it’s not as practical as ISL, but, curious if anyone here actually needs to use ESL for their work at all, or has needed to …

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