I've seen Americans overseas who insist on removing shoes and belts, even when the security personnel tell them it is not necessary. What would happen if I were directed to a TT line and I declined? Or went to the line, but proceeded to take off shoes/belt/outerwear, empty pockets, remove laptop and LGAs? Saw a post about someone who was sent to the TT line, forgot a bottle of water, and was written up on the spot, presumably because TT's are being held to a higher standard. Now that's one thing if you've 'opted' in for TT, but perhaps if I have GE/Nexus, the benefits of random 'expedited screening' are offset by the threat of jeopardizing/losing GE/Nexus because I forgot a water bottle at the checkpoint (something I do frequently). Or, perhaps like some Americans abroad, I have worked out my little routine, I'm often jet-lagged or thinking about 40 different things when I'm travelling, and since TT isn't always available, I just don't want the hassle and guesswork. Note: I do actually remove my shoes before the checkpoint. I sit down, remove shoes and put on 'airplane socks' to protect my feet/regular socks, and approach the checkpoint that way. After the checkpoint, I remove the socks and put my shoes back on. Since I will never know until the TDC whether or not I'm going to be selected for the TT lane, I'm not about to change that part of my routine anyway.