I've had it be anywhere from 2 minutes to over an hour. If you're at the A screening, take the right side and go as if you want to go back down A concourse. You'll get through much faster since there's three stations instead of the 1 off to the left for the B/C/D/F connecting people. After you get through the A screeners, just turn left and you'll meet the people coming out of the B/C/D/F station and be on your way. Last time I did this I picked up about 15 minutes...would have been more if I'd realized how many people were waiting to go off to the left instead of going straight.

Biggest problem I ever had was when several transatlantics arrived back at once and the NBA All Star game had been in PHL for the weekend. Feb 2002, and they still didn't know exactly what was going on...