It really depends on the field. I will talk about fields I know: fundamental math - one paper every 2-3 years is a good pace, every paper 50-100 pages. AI - a paper a month is the usual, with a hard cap at 10 pages, often less.

They could also be directing thesis. They'll appear in their students papers on the topic. My professor was incresibly useful in mine, and I know he does this a lot.

There's a guy at IBM who has thousands of patents with his name on.

He works in the department that helps people write patent applications.