I'm aware of this to an extent. Do you know of any list of what degree of parallelization to expect out of various components? I know this whole napkin-math thing is mostly futile and the answer should mostly be "go test it", but just curious.

I was interviewing recently and was asked about implementing a web crawler and then were discussing bottlenecks (network fetching the pages, writing the content to disk, CPU usage for stuff like parsing the responses) and parallelism, and I wanted to just say "well, i'd test it to figure out what I was bottlenecked on and then iterate on my solution".