I am an inland applicant too but they made me give them the medical exams twice while the first one was 10 month old and still valid. Moreover, while my biometric is still valid l was requested for another one too.
They don't seem to know how to do their jobs. It is very subjective and luck plays very important role. There is no way that one can make a reasoning for the progress. It may relate to the applicant's origin country, gender, age, etc. The processing time for female applicants seems to be much shorter (faster) than the male applicants.
Also, it may be the case whether or not you are already paying taxes in Canada. If so, why they want to give you permanent status quickly? You are already here. So, let's bring more labors from overseas for more revenue.
