Genuinely curious: is it even still relevant today? I've got the impression that there were a lot of these elaborate techniques and algorithms before around 2016, some of which I even learned, which subsequently were basically just replaced by some single NN-model trained somewhere in Facebook, which you maybe need to fine-tune to your specific task. So it's all got boring, and learning them today is akin to learning abacus or finding antiderivatives by hand at best.