I took Brix readings from each of my plants, weekly, for a couple years, and I didn't find a very close correlation between "training" and Brix. The numbers usually ranged between 6 and 14 and rarely changed more than a point or two between readings. I'd find more variation from hour to hour than I'd get from week to week. If, for instance you only measured the daily temp at 2:00 each afternoon, you could see how the weather changed over time, but it wouldn't tell you much about each day. Brix is a lot like that.
Foliars and drenches applied in the morning will affect Brix by the afternoon - it's a very quick reaction - a moving target. So I concentrate more on keeping things balanced over time. If I saw that Brix had dropped a couple points between readings I knew that that plant needed some extra attention, and I'd look it over and try to decide what it needed.
I also never varied from the schedule and ran on the light end of dosages, so it was easier to see a difference if I doubled up on a drench. Now I'm just using intuition, and doing a little better ... maybe. At least the lack of rigidity is easier and more fun for me. But the schedule works - no good reason to vary from it until you get a feel for the natural way that plants grow under this method.
I actually don't remember a plant "needing" DeStress because of training. But I never did the harsh stuff - just topping and bending. If you do a lot of branch tying and leaf stripping, then it's probably a good idea, otherwise a regular shot of DeStress every week or two never caused me any issues.