For every time I have encountered a TSA pre line that is closed or as long as the regular line, there are 10 times where the line is open and it is a clear advantage. I have used it since the very early days where it was only at a one DFW terminal and was by invitation only to high level AA elites.

To me, the worst period was when they were giving it to random pax, usually elderly, on a one time basis. They had no clue what they were getting, had to have it all explained, and gummed up the works as they took off their shoes and then had to put them back on again.