Every corporation, firm or individual doing a banking business in this state has the privilege and option to suspend business activities completely or partially on Wednesday, Thursday or Saturday mornings of each week and shall not incur any liability for failure then to exercise all of the lawful functions authorized by law; provided, that nothing herein shall be construed to compel any corporation, firm or individual doing a banking business in this state to suspend lawful functions on Wednesday, Thursday or Saturday mornings of each week.