@ cjg1987
Don't be too surprised when you find out that a May 20th applicant is getting his/her application reviewed. Here's how I think CIO operates. They have dedicated officers who handle one or more NOCs. For example, there could be a few officers who just review NOC 2174 or related occupations such as NOC 2173, NOC 2171, etc. I think the reason why the mechanical engineering applicant who submitted his application on the 20th of May is getting his application reviewed compared to a NOC 2174s whose applications are in the first week of processing is because the low volume of applicants in the mechanical engineering category.
Hence, I anticipate an applicant in the petroleum engineering category who, for example, submitted his application on the 20th of July will get his/her application reviewed fairly quickly.