You must have your own cover in addition to what your employer may be offering you today. Employer’s cover may disappear any time (company may withdraw this perk, your new employer may not have this cover, you may decide to start your own business), while your need will be there, till all your family responsibilities are fulfilled and you must have a policy to cover this risk associated with loss of family income (due to death, partial or full disability).
There is special cover available for some 25-30 main Critical Illnesses (like cancer, heart operation, organ failure).