The US has been amending the constitution about once every generation or so the last amendment was in 1992.

Spain changed the constitution in August 2011 https://www.theguardian.com/business/2011/aug/26/spain-const...

It was to satisfy banks, but for the sake of your argumentation, they changed it.

Sure, many countries change parts of their constitution from time to time, usually through a parliament. The question was however: "So every generation has to vote a new constitution?" because earlier someone was questioning the Spanish constitution since "no one under 57 has voted on it".

It’s the same thing.

You would also want to note that many constitutions in Europe aren’t that old many were rewritten following WW2 and those which weren’t are often modified and ratified.

There is no legal difference between adding or removing parts of a constitution and voting on a new one.

You still need to approve a new constitution and ratify it. If you start from scratch it means that you either didn’t have a codified constitution or it was really shitty but those are pretty unique cases.

I really don’t see a problem of revising a constitution once every 25-50 years.

I don’t think I follow.

What is then exactly now the difference if you compare Spain with other countries?