There are lots of different things that can compress a nerve. Disc issues are most common and they can be central or lateral disc herniations or they can be extrusions where the disc breaks off and moves and compresses the nerve in a different place. Arthritis and enlargement of the joints in the spine can compress nerves. Anatomy/genetics play a part. Cysts are common.

The point is that you could be getting compression at a number of different locations in a number of different directions from a number of different sources. What might work for one person with stretching might make another person feel terrible.

A therapist will often move a patient through a variety of positions to try and figure out what might work. But there are no absolutes or always treatments.