must you stick to the routine?

i know that after about a month you are suppost to change up your exercises to confuse the muscles , but i was just curious , can you change the ex's  every week? or is it bad?
 because today im doing my bi's and chest. and for chest i usually do incline bench with DB's and flat bench with DB's
and then use the machine.. that does like flies.
and today i was looking up some other ex's and thought id like to try them today , its only my 3rd week.
 so i was wondering does changing it up more often then one month  harm any?

Rather than changing the routine to confuse muscles, you change it so they dont get USED to the routine and the muscles can respond better. I `ve read that Pro BB`s (BB=BodyBuilders) with just changing the angle of position they work out the muscle different.

In my experience you should stick to at least 1 month to change the routine, but if your muscles start getting USED to the exercises you can change the order of the exercises you do in this routine. I think the name of the machine you are talking about is the PECK DECK.

It doesn`t harm any, but you shoud learn the basics and get really USED to them, before moving forward with new exercises.