There are different situations. It has happened to me more than once that I walked past a guard, but I immediately reported it to my opponent and simply returned to the starting point (I almost always do the same with those who have passed a shifted guard and told me about it themselves). Sometimes it's simply impossible to see it. I had a game where my scout hero was moving off-road, and when transitioning from one grass tile to another, there were two passages — one guarded and the other not (visually, it looked like a continuation of my respawn). I went where I thought my respawn was, and based on the 2 wood mines, I realized I had crossed the border and that the guard was supposed to be guarding this particular passage, not the one where it was standing. How can you say that this is a gross violation? It was simply impossible to recognize? And simply turning around and going back is a loss of tempo. If my opponent had demanded a tech after that, I would have agreed, but I'd hardly want to play with him after that!