BNSF and possibly the UP have a feature, to "recall" the last transmission, in case the cndr was asleep, and didn't catch the axle number......
Some congested terminals, have them set, to only xmit on defects detected, although I don't know how you would know it's working, other than the initial transmission, with the detector location. I have some sweet "PowerPoint" pictures, in my computer, from a wheel that lost a giant pie shaped piece, from a train of mine, at 49 mph. 13 miles later, we swapped crews, and only the "roll-by" rule saved them from taking her up, to 70 mph. (If anyone knows how to take pix from a powerpoint program, and share them, let me know, and I will add them here) They were emailed to my, by the BNSF trainmaster, at Clovis, after the wheel was changed out. I do have the largest piece, that broke out, and it weighs in, at over 100 pounds.........