The placebo pills are not needed for protection. They're just reminder pills so that you don't get out of the habit of taking a daily pill. But if you'll remember to start up again after seven days, then there is no reason to take them. Unless of course, you're on Mircette, where those pills contain tiny amounts of hormone to lessen estrogen-withdrawl symptoms. But unless you are on that pill, then no, there's reason to take the placebos.

You are ALWAYS protected on the pill, even during the placebos, so long as you take all of your hormone pills correctly. :) The reason the pill is in a three weeks on, one week off formula is because it was designed that way to mimic a woman's natural cycle. :)