It works pretty much like when you apply to a job or a school or for your study permit or permanent residence, etc. The applications are typically processed largely in chronological order, but for any "specific" application, it might be out of that order because of individual merits and circumstances. For example if someone has a part time studying history their application will be more complex and takes longer to process. Also different visa office and visa officer may have a special workflow at their own discretion. It's not like queueing to get a PS5 in Bestbuy where you *know* you're going to be the next if your friend coming together with you just got in. Given that, plus the estimated processing "status" (not the processing "time", which is inaccurate) from IRCC, it could be a good idea to reach out to IRCC (call them, web form, etc) if it's well beyond their processing window. E.g. right now they are finalizing most (80%) applications from the week of May 8, so call them if you applied in May 2 or something.
Based on the data I collected, apart from a very few exceptional applications which got approved in a very short timeframe, all "regular" cases are "generally" process in the order of submission. You can check the data trend and predictions in one of my previous comments in this thread. Inland PGWP has been slow since mid-May, but rather "stable", comparing to other programs like overseas visa, and permanent residence, where some 2021 applicants got approved and some 2019/20 applicants are still waiting.