I think the most valuable thing you can learn depends on what you already know.
If person A knows differential equations but not regressions or Python, and person B knows Python but not the other two and Person C knows regressions but not the other two then the most valuable thing they can learn in an hour will be different.
It might also depend on their goals (does person B want to learn data science of websites)
If person A knows differential equations but not regressions or Python, and person B knows Python but not the other two and Person C knows regressions but not the other two then the most valuable thing they can learn in an hour will be different.
It might also depend on their goals (does person B want to learn data science of websites)