What do you think of having different intensity/rep/scheme days? Not to say a Heavy/Light or High Intensity/Low Intensity. Just recognizing the fact that the body works in cycles and trying to work with it rather than against it with recovery a major consideration, not just training. Just trying to understand the logic with this German training.
The weight should be half of your 1RM, so there's no need to really be lowering anything as it's totally doable. If you need to recharge, take a day off, have extended rest breaks in-between sets (although that takes up more time, and GTV is a time-consuming method anyway) or if you want to replace a compound with an accessory lift (i.e. Squat with a Leg Extension) then carry on.
In all honesty, it wouldn't be traditional "GVT" if you started tampering with the rep scheme. That's just my opinion.
Or you could do 8x8. That's a good one. I've found that when I hit the 8th (final) set with this method I am exactly on the sweet spot of my best sets have just been done and now my form will fall apart (similar to GVT that way. Your form WILL fall part after set 7, but you get your best returns on the following 3 sets). But the weight has to be heavier than 50% of your 1RM from my experience. 65-70% works best with the 8's.
As said - Mon, Weds & Fri (GVT days) with low intensity cardio (think walking, swimming or even just recovering in a sauna/steam room/epsom salt bath. Or maybe even have them off completely depending on how you feel) on Tues, Thurs & Sat
should be perfect for allowing you to hit the next day of GVT training with maximum freshness. I've always felt good adopting these strategies.
I do find that the mental aspect of it is as draining as the physical side of it. Ten sets of anything is no joke and WILL get boring. But it's a great way to shake up your training even if for a week or two.
Try it! See what you think... ;-)