I learned an industrial BASIC in a few hours if you add it all up. Learning how to use it reliably took weeks with safety mostly coming by default. Learning that for large stuff took several months where I learned programming practice. How long do these milestones take for average C developer with what productivity? Note that my Pentium 3 at 400MHz could compile the compiler in a second or two. Fast iterations. :)

Learning C was a different experience entirely. The mental work involved was huge with the level I worked at for any job being micro-managing the machine. It's only simple on the surface. The job is much harder than a BASIC, Oberon, or whatever with selective use of unsafe features.