I do believe CO can do better. Hence I agree with anyone saying that - "He is a partner in this crime" or that he is riding the gravy train...
Not picking on Spec but using his update to put forth my points :
a) Since Consulates are closed, CO should have the number from Consulate as ZERO [0] in his calculator or Excel or any tool he uses.
b) CO should not have "some" idea but clear idea and number based on "Preadjudicated" cases.
CO can do the above two for sure and should not give any excuses.
The folks who are responsible for transporting the paperwork from Storage to location - should clearly review their performance. Dude, If this is your Job and you are getting paid for it - Do it on time and do it efficiently.
If this is too much of an ask, do consider hiring us [immigrants] and we can show how its done.
Imagine if a lawn contractor, or plumber or handyman that you use - give you the excuses we have been seeing in doing their Job [Keeping updates straightforward, do their work and bill for only what they do] - We would have fired them longtime ago. For christsakes, we are not asking for grace or help or relying on luck - DO THE JOB...

Originally Posted by
Spectator
The process for visa allocation is explained quite well in
this document.
CO gets exact numbers from the consulates in advance of the FAD calculation and VB publication. The exact number of visas are allocated (at the time of VB publication) to each consulate based on the FAD movement, based on the reports each consulate submitted. If the consulate cannot interview the candidate and make a decision, then the visa is returned to CO in the following month.
CO appears to have some idea of preadjudicated cases that USCIS has (in his "pending file") . A visa number for AOS cases is not allocated until USCIS perform the actual approval and request the visa. During a month, not all cases approved by USCIS were preadjudicated and in the "pending file" that CO has access to. Even though CO sends USCIS a list of the cases in the "pending file" that have become current, that does not mean that USCIS can approve all those case in that month. That may be because additional information is required (e.g. up to date medical) or the much talked about processing capacity, or it might be that the paperwork does not make it from storage in time to the location where the case can be reviewed and approved.
That is my best understanding of the process, but I do encourage people to read the DOS explanation of the process.