Like everything that has to do with TSA and their Canadian equivalents, it seems to be wholly a function of which "bozo" is working that day. I was through MSY a couple of months ago, and simply dropped my bags at the end of a long line of bags, flashed my boarding pass to that to "guard" watching the end of the line, and proceeded on my way.

In ORD, which is fast becoming my favourite airport, the X-ray machines are "behind the scenes" so you simply check-in like you always did, dropping your bags off at check-in. (And apparently they are so confident in the X-rays at ORD, you may now take a different flight than your checked baggage.)

I've had it both ways in LAX, over the past several years. Last year I had to essentially identical connections in less than a week. One time I had to wait in line (there were only perhaps 10 people, so it wasn't too bad) while the next time I was able to just drop off my bags at what would have been a much longer line had there been people standing next to each bag.