Point of reference: I just went through IAD security at 4 PM today (Sunday). Very unusual that there was *zero* line for the document checker (although full second-boarding-pass check and hand swab was in progress). It still took 17 minutes (timed with a timer on my Android phone) from the time I entered the area at the top of the escalator to leaving the checkpoint. Note that there were 6 x-rays in use, compared to the 4 that are usually operating on Monday AM. Another 8 minutes from the exit of the checkpoint to the Admiral's Club in Concourse B.

Total 25 minutes. Add the 10-20 minute gate cutoff for the airline, and you're out of time if the interview takes more than 15 minutes.

And that's with no lines for the document checker. On a Sunday.

YMMV.