Just like zomb said...You need to shock your body if it stops growing...
For those 10-12-16 whatever weeks your cycling you're like superman...Your body does everything a milion times quicker..
I always like in the middle of my cycles to change my diet and traning completly this way you're body is in a "shock" and you keep growing big time...
You body can get used to almost everything....so changing every now and then is great...
I think about it as doing the same cycle every time...It will never give the same resaults and the first time this is why you always change and adapet to diffrent cycles and
substances...