If you look at the German one (it's the one I know best) it took in learnings from a) failures of previous iterations in German, but also b) from constitutions

If you look at the German one (it's the one I know best) it took in learnings from a) failures of previous iterations in German, but also b) from constitutions like the American as the Allies consulted and had to agree on it. Maybe the American survived for so long as for one it changed quite a bit over time, via amendments and via interpretation. And mind: America had a civil war ... but then found a way to reunite under the constitution (with three amendments) that could also have torn it apart easily.