DA is always off a bit, although it's better now than a year or so. They did an update and it's a little more accurate than it used to be. My previous vehicle it was always within 6 hundredths of the time slip (I always shallow stage) aside from one track way out in middle of nowhere that I saw it be off by .2 seconds.
This year or maybe it's just the ST, but I've had it be pretty far off the time slip, always slower than the slip. A week or two ago it was off by almost half a second on one run, and .3 seconds on another run, and then it was within 2 hundredths. I don't trust it like I used to, but it's still a good measuring tool if you use it enough to recognize a legit run vs an anomaly. Not gonna lie, it's kind of nice seeing a crappy time on dragy as I'm pulling off the end of the track, then driving up to the time slip shack and being handed a slip with a good time on it.