OK, firstly, in order to schedule a CP case the visa office needs to allocate the needed visas for each person on the case. So - when you see an embassy taking 40 cases, including 85 people, the VO allocates 85 visas to that embassy for the month of interviews. At the end of the month the embassy has to account for those visas, returning unused visas to the pool (which can then be used for other cases). So - they return visas for no shows, denials and AP.
Now contrast that with AOS. There is no pre-allocation of visas. The last processing step after the interview is for the IO to check a system called IVAMS, and "draw down" the visas needed from the case. That system has direct, live access to the VO maintain numbers. So - we did have a year where AOS interviews were concluded successfully but no visas could be issued. That happened about September 9th.
The CP visa recycling will happen at the end of August so there will be visas at the beginning of September. However, there are about 7K AP cases in flight, so if they clear them, they will be drawing from the same pot that AOS draws from. Things are tight because I estimate almost all the 54850 have been scheduled. The SaveDiversity Ready number is overstated, but we do know that at the end of July there were about 30K issued and then KCC scheduled over 24K people in August and September. So - very close to all being scheduled. I expect about 4K, perhaps 5K recycled visas at the end of August, and KCC reported they sent 708 cases to USCIS (about 1400/1500 people).
Frustratingly, the process as previously implemented (meaning unless something changed for this year), does not allow visas from September refusals to be recycled - and there should be some since there are about 10K people scheduled for September (so I would expect 2k refusals). Some of those can be recycled within the embassy (i.e. used for their own clearing AOP cases), but the majority won't make it back to the VO, and therefore IVAMS. This means the year will almost certainly not hit the actual limit, BUT KCC might refuse to schedule/allocate more visas as it won't see the embassy returned visas until it is too late to use them.
Bottom line, not trying to scare anyone for fun, people should understand the position we are in and do what they can to get their cases concluded asap.