If anyone wants to practice the given method, and explore its uses, here are a few experiments to do while projected:
Have a friend or spouse set up an object in an adjacent (open) room in a prominent location. Try to walk there and view it.
Physical barriers
Try to walk through a door.
Put a picture on a door beforehand, and then try to walk through it.
Put a mark on a door at one end of a hallway, and another mark on the other side of a door at the end of a hallway. Close both doors, and try to walk through the first door.
Try to cross a river.
Touch an electrical outlet.
Interaction
Try to interact with an animal.
Try to interact with a person.
Try to interact with an inanimate object.
Try to cross bars.
Try to cross a line of salt.
Try to fly, or jump very high.
Apparently there are things which you can normally do, which you can't do when projecting, and things you can do then which you can't normally do. Don't expect to be able to do too much too soon.