Same here. I've used it primarily at SLC and LAS, and a few other random airports like ANC. I've had literally no waits every time. Last week I had a very very early departure, and was at security around 5:30AM. The precheck line was actually still roped off. I went down the SP line, got three beeps, was informed that "Today, you get precheck. Please proceed to..." and went to go through. Even though the entire T2 security empty was empty (and I know for sure the other TSA agents heard the very audible 3 beeps), they still got upset with me when I didn't take my laptop out or remove my belt (yet, they had no qualms with me wearing a coat and shoes...). That's the only time I've ever had an odd experience. Maybe they just weren't paying attention.

On another note, this last Saturday, I was walking past the T1 security area at SLC on my way to T2, where US/AA/UA/WN and everyone else checks in. There was a bottleneck in the ridiculously-long lines, and sure enough, a TSA agent was standing in front of a stand with an iPad attached, randomly pointing to her left or right. I've read reports of others seeing this, but it was just a bit strange to see it in real life.