If you look around on this forum, you will find many posts recommending that you stow all valuables in one lockable compartment before putting your bags on the checkpoint xray belt. You don't have to use zip-ties - any lock will do.

Silly story. I came through the NoS grope a month ago. My rollaboard had just cleared the xray and the TSO standing there was about to open it. Oops. It was locked, of course. He looked around just as I stepped up. Then he asked if it was my bag. Yes...he says he needs to check it, can I unlock it? Sure...but I couldn't find my regular lock that morning, so I had locked it with a padlock. The key was in my small carry-on, which hadn't cleared the xray yet.

Carry-on finally comes through, and he watches while I undo the combination lock on the carry-on, remove my keys from inside, and unlock the rollaboard.

(The 'suspicious' item was two barbecue sandwiches from a local popular barbecue place).

Most of us who have adopted this practice did it because we had a TSO dip into our bag without our knowledge and out of our view. In all fairness, if could also be a pax who dips into your bag while you are delayed going through the WTMD/NoS or waiting for a grope, although pax don't have xray vision like the TSOs do.

A TSA supervisor in KOA was fired a couple years ago for stealing from pax at the checkpoint. She would watch the bag go through the xray (so she knew the exact location of wallet, valuables), pull the bag for a 'check', turn her back so the pax couldn't see what was going on, and steal things before returning the bag to the belt to be re-scanned. (In some cases, the pax were probably hung up going through the WTMD/scanner or otherwise not in sight of their bags). Technically, other than stealing from the bags, she did nothing wrong according to TSA SOP (pulling the bag, looking through it without identifying the owner or allowing the owner to watch, carrying it back to the front of the belt to be re-run through the x-ray).