I don't know but I can definitely tell you that each IO would grab a case of
files. Then go through them for EAD/AP with RD order. This process would
end up put earlier RD case at the bottom and the last one on top. Then s/he
would later come back (when GC visa numbers are available) to process 485
cases for this pile. Now the top one (RD latest) get approved first and the
second one .... I cannot say all IOs do this way but the one who handled my
case certainly did. For EAD/AP, I saw cases in front of mine got approved
first, then mine, then the one behind me. Later, for 485 cases, the one
behind me got it first and then mine. Two working days past, about 10 cases
in front of mine are still in "Initial Review".