Let's say take German volume training's 10 set idea with the first 5 sets being 5 reps(heavy) then 5 more sets of 10 reps. Just 10 sets a bodypart a day like gvt setup. Would this be overkill or a good routine for strength and mass?

I'd almost rather see 5 sets of 5 heavy then after the last of those sets cut weight by 50% and shoot for one 30 rep burnout set. I'm not quite sure that after a 5x5 you'd be able to do a heavy enough weight for the next 5 sets of 10 (remembering that in theory in GVT the weight is supposed to stay constant) to be worth it. Theres some research that shows the 30 rep set within 30 seconds of the last working set does help though.
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I see your point i figured the weight would have to be greatly reduced in order to carry out the last 5 reps maybe adding no benefit other than a good pump. Maybe a 6x6 routine would be more beneficial.