Countries that are the most prolific constitution generators tend to be among the least stable: The record is held by the Dominican Republic, which has had 32 constitutions, followed by Venezuela (26), Haiti (24), Ecuador (20), and Thailand (17).
It doesn’t matter how lengthy the final document is, apparently. The longest current constitution – almost 120,000 words – is that of India, which is a thriving secular democracy. The shortest is that of the US.