Just wanted to tell my experience. Was skateboarding at the skatepark, had a terrible fail and hit both of my wrists against the ground.
Went to the hospital for X-ray only on the right wrist because I knew it was broke and didn't wanted to have two casts... Turned out i broke my scaphoid (3 fractures in triangle shape) on the right wrist. They wanted me to have a surgery but I just took the cast because I was abroad, it was cheaper and I didn't wanted to have metal things in my wrist.
I don't know for the left wrist but i think it was fractured too because it was almost the same pain. The scaphoid bone is the longest to heal due to poor vascularization of the blood at this spot. Long story short: I wore the cast for the whole summer and after they removed it I had more pain in the casted wrist 4 months after, while it took only 3-4 months for the other left wrist pain to vanish.
I did a lot of rice bucket training for rehab after they remove my cast. I can do pushups again without pain.
I think casts could help to not worsen the bone placement due to bad movements but not for so long. The new generation of casts, those who can still be a bit flexible so that there is still a bit of blood circulation, could be good.