While emergency contraception is safe and effective for occasional use, it should not be relied upon as a regular form of contraception. Repeated use within a short period can disrupt your menstrual cycle and may not provide the same level of effectiveness as regular contraceptive methods. If you find yourself frequently needing emergency contraception, it's advisable to discuss more reliable contraception options with a healthcare provider.
There are some occasional instances where the egg might already have been released, and this is why the morning after pill is not 100% effective.