This a quote from Andrew Read from Breaking Muscle that rings so true. For the full article, go the Physique Factor page on Facebook and read up.
Back when the only training information you could find was a bodybuilding magazine, a lot of articles talked about muscle confusion. Muscle confusion was this idea that by using a different workout every time you trained you’d make more progress. The only problem with that idea is this little principle called SAID – specific adaptation to imposed demand. SAID says you get good at the things you do repeatedly.