FYI I have just finished a six segment mileage run in the US using a DONE3 ticket that was completely open dated with reservations made separately. I had absolutely no trouble at all with the ticket - though I did get a few raised eyebrows at check-in with two consecutive overnights consisting of SFO-MIA-DFW-SFO & SFO-ORD-DFW-SFO. (I am now an AA Platinum)

However, apparently since this ticket was on BA stock issued in Hong Kong (and perhaps because I made the reservations only two days before) I got "randomly" selected for gate screening 5 times out of 6.