They get enough practice that it becomes easy for them to go where they want to go. We encourage them to explore and try to laugh with them when the landing spot they choose turns out to be not quite as stable as it looked. They learn that the play gym is a good place to land. Ron and I are usually fairly stable. Grandchildren are okay if you don't surprise them.
Door frames are good.
Our home is as safe as we can make it for birds learning to fly. Flight lessons are strictly supervised. In fact, all play outside the cage is supervised. Our babies stay here until they are good flyers. We give them a gradual wing clip before they go to their new homes.