Not Switching Up your Routine
 

If you are doing the same exercises for the same number of reps/same weight, you won’t make much progress at the gym. Mix up your routine, shock the muscles and progressively overload them – meaning your lifts should be increasing over time. There are tons of great routines out there you can follow, so there really is no excuse not to change things up every once in a while.

absolutely, you cant just keep doing the same'ol routine everyday and expect your muscles to keep growing, you must sock the muscles and keep them guessing, I would at least change it up every 4-5 weeks, for example if your trying to 'bulk" I would add a day of just high reps every week just to shock the muscles, also go from machine to free weights and always change up the exercises for each muscle group....ANGLES IS THE KEY!!