Hey Skeptical,
I would ask him but I don't have a twitter account. I suspect most of these fortifications are unmanned or lightly manned. Many of the experts, or "experts" as the case may be, say it will come down to ISR and logistics, which is why some of them are predicting major breakthroughs. But they are guessing, like everyone else.
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Western partners have told him, he said, that they now need a “next example of a success because we need to show it to our people. … But I cannot tell you what the scale of this success would be. Ten kilometers, 30 kilometers, 100 kilometers, 200 kilometers?”
https://www.washingtonpost.com/world/2023/05/06/ukraine-counteroffensive-expectations-hype-russia/