SNSD renewed their contracts in 2014, 7 years after debut, I think BoA keeps renewing her contract and she debut in 1999 or was it 1998
EXO-M or rather China based trainees in SME were the most abused as it seems the company was making contracts with them as trainees which is probably why many EXO China Members got out.
Anyway the basis of why JYJ were able to leave and sue SME was based on Slave Contacts or what it has become known as