Generally, the body panels and windows of a State Trooper's cruiser provides, to be anal-retentively technical, concealment, and not much cover to State Troopers hiding behind them. Failing to distinguish between the two conditions, or to understand when both are combined, may result in injury or fatality to the Trooper.
Interestingly, my friend's little Cabriolet ("Fahrfee") died on Route 78 due to a bad alternator (en route to the Kutztown, PA Folk Festival) and she pulled over to the shoulder, with me behind her. State Troopers pulled behind us, but didn't do any diagonal parking. Just lights a'flashin' and good smiles all 'round. Didn't hurt she was wearing heels, a halter top, and looks like a fashion model from a '69 Cosmo.
Earlier that afternoon, when I'd driven to jump start her car the first time before I figured out it was the alternator, the Saucon Valley (PA) cops with their two Expeditions pulled over, but again not at a diagonal. So, predicting the possibility of a threat doesn't seem to be in the training; they didn't run her plates in each case, to see if she had any outstanding warrants, until after they'd pulled over and done the whole, "Need help here?" routine. Which they provided, I might also add, with a smile, amazingly so (they even blocked the right lane of traffic to allow me to turn around and face her car, and kept the lane blocked until she was up and running under her own power).
--Scott