Changing routine and getting used to routines

[DJ66]

How often should you changes your routines? when doing normal exercises you should changes your routines quite often so your muscles don't get used to the routine your doing, but how much change constitutes enough change to stop them getting used to thing? Does adding a few reps help? or should you change your whole routine adding in new exercises? or should you stick to the same things so your body gets used to it and sees whats happening and grows because of it?

 

[DLD]

How often should you changes your routines? when doing normal exercises you should changes your routines quite often so your muscles don't get used to the routine your doing, but how much change constitutes enough change to stop them getting used to thing? Does adding a few reps help? or should you change your whole routine adding in new exercises? or should you stick to the same things so your body gets used to it and sees whats happening and grows because of it?

I will stick with a routine if it is working, if I remain without gains for 2-3 weeks I will add reps and turn up the intensity, if that produces nothing then I will re-write my routine.