what is pre-adjudication - Recap
Based on the procedure listed below it appears that DOS will tell USCIS which per-adjudicated cases get visa (GC) first:
If USCIS requests an immigrant visa number for a case that is not current, the request is moved to the "pending" file with the DOS. Data from this pending file is used by the DOS to calculate the appropriate cutoff dates for the backlogged categories in the Visa Bulletin each month.
Cases placed in the pending demand category are processed as immigrant visa numbers become available. The DOS communicates with the USCIS regarding the A numbers of the cases for which visa numbers have been authorized. These cases are then processed to completion and green cards are then issued by the USCIS.
This seems to be a streamlined process, with actual visa numbers tracked, issued, and assigned to particular green card cases as part of the approval process.
Bottom line: As per this USCIS randomly picking low hanging fruits should not be the case at least going forward.
For additional details regarding this theory see Ron's "What is "per-adjudication"?
http://www.imminfo.com/News/2012-10-...udication.html
Lets hope DOS and USCIS together enforce/implement strict rule of FIFO starting this year...