Comment by smelendez

Doesn’t it vary heavily?

Auto mechanics usually are required to bring their own tools to the shop. Historically civil engineers working on paper often brought their own favorite mechanical pencils, calculators, and slide rules.

Back when paper manuals were more common, it was pretty common to see software developers have their own dog-eared O’Reilly books in their cubicles, and those were probably the closest predecessor to something like Claude.