I will second the info on waterbury. performing compound movements, especially those related to back (rows, pull ups, t-bar) will work your arms significantly enough to grow. Adding extra arm movements (curls, preacher, ect) can lead to overtraining, and thus stall out your growth.

I would drop the isolation arm movements, and stick to compounds. Atleast for a few weeks, then slowly add in isolations, but keep the frequency low, and the wieghts heavey. then back off again.

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