This is what you call the razor blade method! a fast way to knock down runs! Instead of wasting time block sanding it and hitting the areas all around it, you're able to focus more on the run itself with the razor blade. But please note that this isn't the only way to remove runs! It's just a faster more efficient method that I prefer. But key to this is making sure you have enough material on the panel.
![](https://i.ytimg.com/vi/_Ft7eX8PD8A/maxresdefault.jpg)