The reality is, by 1936, the only serious fortification line which had that sort of directional line was Maginot. The Stalin Line was in place too, however, it was nowhere near as strong as Maginot.
Such a feature does belong, however, the only places which I can see anyone building such a line would be the Dnieper-Daugvala line (sorry, spelling, had a few drinks), or an extension of Maginot. With the exception of mods (eg HoI3 equivs of Mod33/34) there would be no real provocation for the construction of such a line, as everyone will be pumping IC into divisions for the actual fighting. And remember, there are more provinces to hold such a line, which means such an extension of the line will be both costlier and harder to hold. (The entire Belgian-Lux border?! As well as the German border?!?!??!)