The timing of receipt of the Biometric Validity Letter (BVL) may be indicative of whether or not your application has been approved.
If you did not submit an upfront medical exam report and IRCC never requested medical exams from you, but sent you a BVL instead, then it's more than likely your application has been refused.
When you apply without submitting upfront medical exam report, you either get a request to do your medicals or you get your BVL followed by a refusal letter. Most people I know who got their study permit applications approved, received their BVLs same day as they received their Passport Requests (PPRs). This was way after they had received the medical exam request and had passed the medical exams. I received my BVL and PPR in the same minute.
All the best to all.