Consider the following statements about the action and usage of contraceptive pills and identify the INCORRECT statement 

Statement I: Contraceptive pills are typically taken daily for 21 days, with a 14-day break.
Statement II: They work by inhibiting ovulation and preventing the implantation of an embryo.
Statement III: Saheli is a ‘once a week’ pill with very few side effects and low contraceptive value.
Statement IV: The pills are most effective when started within the first five days of the menstrual cycle.