My answer: Yes. More than a few times in my LE capacity, and on one memorable occasion while on my own time. My girlfriend and I were sitting in her parked car in the parking lot of a local Recreational Center, after dark [I was in my early 20s and didn't know any better]. Her car was parked near the building, with the front of the car facing the street, and the rear of it facing the building's front. While we sat talking, I noticed two guys walking by in front of us, about 30 feet away. They pretended to pay us no mind, and they walked on, going behind us and disappearing around the corner of the building. However, I kept my eyes open and about 30 seconds later, I noticed one of them peeking at us around the corner. His buddy reappeared with him, joining him as they both watched us intently. I was armed; I had my S&W 645 with me. But I was also armed with something else, namely situational awareness. We immediately made a very hasty retreat, and that was my last time "parking". As I've said before: Mighty hard to lose the fight if you're gone when it starts.
Seen on a bumper sticker: "Exercise. Eat right. Take vitamins. Die anyway."