It SOMETIMES work...
You may skip the placebo pills and end spotting or bleeding anyway, and it could last for 2 weeks, which is also a common occurrence.
You are still protected from pregnancy. Your period does not make your protected, your hormone pills do, so skipping a period and starting a new pack cannot affect your protection.
It CAN delay your period until you stop taking pills to have a period, or you can wait to the next months placebo pills.