>Writing a complex parser or certainly a compiler is a 1 - 3 month project, for example.

1. Estimating time completion of something that has been done multiple times before and an open problem that has not yet been solved is a different matter entirely. 1 to 3 months is an educated guess and more likely than not, an underestimate.

2. I do not think months long complex compilers and parsers are being routinely completed by LLMs as your original comment implied. Regardless, they are different classes of problems.