Work in NLP. Ever since HuggingFace became mainstream we almost never had to do this.

We used to have to implement the cutting edge stuff ourselves because papers do not come with code, or give code that requires huge amount of work to run. Now they often appear on HF within a few weeks of publication.

The only occasion in the last 2 or 3 years where I wrote a DNN from scratch was when I had to give a short lecture, for pedagogical reasons.