I've had an interesting life and had or was lucky enough to find out about all sorts of obscure things in my working career. I started early in the creative department of an advertising agency, I did the support stuff and had to know enough to double check the orders and things like that and I learned a lot about printing processes, the color standards, the materials used.
It happens that my husband has worked most of his career in box making. Most of us don't think about it, but there need to be boxes made to put other things in. Here in the northwest, the raw cardboard they use is most certainly not acid free unless specified and up-charged. It's also used a market indicator, if boxes aren't being made then that means products aren't being made.
I worked with engineers for most of my career, and there are all sorts of engineers. Most of the time it was civil engineers and large projects like roads and bridges and airport runways. Some of it was with buildings, we specialized in hospitals, military projects, schools, etc. but did "regular" buildings too so we had specialists in glazing (windows), various structural issues, etc. Someone types (and read) the reports, plus I did specifications so picked up a lot of things that have come in handy, like most square floor tiles are 12", can be good to know! Or that ceiling grid is 3x2
One of the really cool places I was only at for about 2 years. It was an environmental firm and we had archaeologists on staff! When you see stories about bulldozers finding things, well that company was one of the people you'd call. Another staff member did wildlife assessments. She would go to remote sites and look for endangered species as well as taking an inventory of all wildlife, including migratory patterns etc. Also learned more about the earthquake fault near Seattle than I ever wanted to know...