You will ultimately encounter the effects of "disuse", training every eights days, especially bodyparts such as upper back, arms, ones that recover relatively quickly will result in loss of size and strength.
It sounds like you need to make some changes if you've reached a state of over training. Maybe just a one or two week break from training. Or, a change in your work-outs, e.g. stop going to failure for 4-6 weeks, or cycle your work-outs, heavy one week, light the next, things like that.
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