Does anyone know why is important for a bank and its customers to place a Reg CC on a check? Iam in training to become a banker and I need to know any ideas.

Reg CC protects the bank and the client.

If the check being deposited is questionable for any reason, such as it's out of state and for a much larger amount than what the client normally maintains or desposits, then place a Reg CC hold is a good idea.

During the 5 day hold for an out of state check, usually the check will clear or not clear. If you have not allowed the client access to this money in the intervening period and the check turns out to not be good, then the client will not be overdrawn. Thi means their other checks written will be paid through and the clients exposure to fees will be minimized.