This is really a good method for opening doors that are locked. The only setback with this, though, is that it only works for outward opening doors.
This method is preferred over regular lock-picking if the door opens outward, because it is a lot quicker. Lock picking can take 5 minutes... When done correctly this only takes 30 seconds! So, if you can, use this.
Learn how to pick an outward opening door with this easy to follow guide.