I'm a 15 year vet from a small rural service. Our local hospital does have an ortho but no relief when he is out. I have used traction in the field about 7 times and put it on for transport on an ER pateint about 4 more. We're hospital based so occasionally have to help out with stuff in the ER. Specifically things like traction that they don't do in the ER.
On every occasion that I have used a traction splint the patient's pain was drastically reduced. These have all benn isolated femur injuries. Rare I know but being a southern state Lots of outdoor activities here and more orthopedic injuries. One specific case was a 10 y/o girl in the ER she had been thrown from her horse no other injuries and severe pain. Pt had come in POV. She was high on the pain scale 8-9 sweating, tears, pale skin. My partner and I went and got a traction splint and we still have Hare's placed splint reduces deformity and the 10 y/o told me that the pain was now tolerable and she did not need medication.
Don't get to use them much but when I do well worth it normally take an adult pt from needing 10 to 20 mg of morphine to 4-5mg for pain control and often no meds required at all.