Pretty common. Take PGA F9 for example - 2 easily reachable par 5s, and depending on tees/wind/apparel boost also 2-3 reachable par 4s. There's a chance at 13 under (23) right there. When you look at these scores you also need to look at the conditions they were played under, whether apparel was on or off, what Tier the person is, etc....
Some people are just really, really good. Whether it be years of course experience, excellent hand-eye coordination, having the putting greens figured out, you name it.