You can also periodize your training. Increase intensity weekly to a crescendo then drop back to 60-70% and slowly increase again. Each cycle try different methods and/or exercises but keep ramping up intensity until your at the overtraining threshold. Constant overtraining can limit gains and lead to injury, might try that partner
thats what i do with DUP...constantly added more volume over a period of time..rarely training to failure...and at first i thought not training to failure wouldn't yield good results but by not going to failure all the time your body is ready to crush weight always and the growth is starting.