Frankly, I think you are exaggerating. My university had a course that required students to build a C compiler that could run the C subset of SPECint (which includes frigging Perl) and this was the usual 3 month class that was not expected to fill in 24h of your time, so I'd say 1 week sounds perfectly reasonable for someone already familiar. Good enough C for a shitton of projects is barely more complicated than writing an assembler, in fact, that is one of C's strong points (which is also the source of most of its weaknesses).