I went through TFW yesterday; it was busy but not overcrowded; maybe a 3-person queue but running at max throughput. At least half of the people grabbed their tray, turned around to go to the repack table, and did a double take, so based on a very limited set of anecdata it was widely used.

People then took their tables to the secondary screening bench to use that instead. Luckily there wasn't much volume coming that way, or there would have been a bottleneck at the belt.