i think it has nothing to do with numbers. it all depends on the batch they send out. since February everything was pretty much moving in a batch. IP2s in a batch, MRs in a batch, PPRs in a batch.
The GCMS notes also mention words such as "batch sent" in the subactivities.
Everyone who has received PPR June 1 and onwards had their MR at the end of February, or beginning of March. So I think that if your application is in that batch, you receive it along with others. If for some reason your application got stuck somewhere along the way, then you get into the next batch or the batch after. Or even get dealt with separately (and receive an odd PPR without the batch like we see once in a while)