Depends on how you requested them. If you gave the AA RTW agent the entire itinerary up front, then some of the segments may automatically be married by the system on connections. When I book (I only use the AA RTW desk), I feed the agent one flight at a time, wait for the agent to confirm that the flight is available in the fare bucket I need (D), and that s/he has grabbed it for me and added it to the itinerary s/he's building for me. When that's all done, then I give him/her the next flight that I want.