How strong was Erens healing pre-Trost? I've seen people say it gave him an advantage in training because of the healing, but i simple wound on the head took hours to heal.

The training was said to be so rough that people straight up died. So wouldnt it be probable that Eren broke some bones given how reckless he was? If his healing really that strong, a simple fracture would be healed in minutes and RBA would have known what he was