and I used to do just that, in perhaps 20-30 times......but the last 3 times in IAH they were quite clear that they didn't want me in the US citizens line precisely because of the extra delay.
Well, at least they did not send you to the back of the queue, as well they could...
Clearly, it seems this matter has not risen to the level of the Code of Federal Regulations or even an internal memorandum at CPB.