Yes, the workflow matters. And it is one reason why Python is popular in the ETL and other processes. You are essentially offloading computation to efficient code while Python simply orchestrates. You probably spend one percent of the time inside Python itself, so it is pretty convenient.
I normally have one "tooling" language that I write all kinds of stuff in. And it goes beyond glue. So performance matters to me.
re: testing, I am pretty old-fashioned. I don't test everything. Only stuff that is critical or complex enough where I suspect breakage in the future. Also, I think borrowing ideas from Ada/Haskell/Clean etc for a new language could solve a lot of these pain points, now that LLMs are writing most of the code.
I normally have one "tooling" language that I write all kinds of stuff in. And it goes beyond glue. So performance matters to me.
re: testing, I am pretty old-fashioned. I don't test everything. Only stuff that is critical or complex enough where I suspect breakage in the future. Also, I think borrowing ideas from Ada/Haskell/Clean etc for a new language could solve a lot of these pain points, now that LLMs are writing most of the code.