Fall-outs can be done on any suspension training device to build "anti-extension" strength. In any anti-extension exercise, the body is forced to resist against lumbar extension and also resist against anterior pelvic tilt. The objective is to instead keep the lumbo-pelvic region in neutral alignment. The inability to do this is what causes low back pain in many exercises.
One of the biggest advantages to training fall-outs is that the intensity can be adjusted infinitely due to the freeness of the suspension device. Any level of trainee can perform and benefit from them.
Make It Easier
To fall-out at a lower intensity, do them on the knees, shorten the straps, or move your body further in front of the anchor point of the straps. Basically, position your body so it's more upright at end range.
Make It Harder
To add intensity, try them on the feet, lengthen the straps, or move further underneath the anchor point. In other words, make your body fall flatter to the ground at end range.
This exercise also allows you to assess your overhead mobility. If you're unable to get your arms over your head via shoulder flexion, you're likely to compensate into spinal extension in attempt to get more range of motion. Don't do that.