I personally always put my film in a clear plastic bag and remove it from my carry on when going through the x-ray scanners. I figure that this prevents any problems should the inspectors decide they want to rescan or randomly search my bag for any reason.
When I did this in Beijing airport recently, the security personnel spotted my bag of film in the tray on the conveyor belt and immediately insisted on hand checking without even being asked.
I found southeast Asia to be very accommodating to film shooters. My bag went through 15-20 x-ray scans, but my film didn't go through any.
I don't even bother asking for hand checking in European airports, however.
I went through Beijing in 2008 right before the Olympic games when security was tight and they were marching through an army of police. I asked for a hand check and still got it. I have more trouble in my home country (Australia) on trying to get hand checks. Though imo it's unnecessary. Just all film has to be carry on.
You should have put 1 roll through that many carry-on scans, it'd be interesting to see if that many scans have an effect.