In the Navy, a retest meant new urine sample.
After my previous post, I confirmed my information with Hubby who was a Navy DAPA. His experience was the same as mine.
Hubby told me that the big emphasis now is on DUIs. Two DUIs and you get kicked out.
Depends on your sex. 
Men face the wall when urinating, so the observer stands behind them, a little bit to the side.
Women urinate sitting down, facing the stall door, so the observer stands facing them with the stall door open.
The rule is, once the person gets the empty cup and goes to the stall, they don't leave until "positive flow" is observed and the cup is filled enough to test. Yes, some people take a lllllooooonnnnngggg time but they can't leave.
It's no picnic for the observer either but we don't hassle the person--we stay patient.
