I read there’s no limit on generations for Italian citizenship, but there are other restrictions:
https://www.italiandualcitizenship.net/italian-citizenship-by-descent/
The story goes that, if we meet the requirements, we only need to fill out paperwork and pay a few hundred dollars for dual citizenship USA and Italy.
It’s probably more complicated than that, but it’s easier than the process other people would have to take.
Before March 17, 1861, there were no citizens of Italy as Italy was not a nation before this date. For a jus sanguinis citizenship application to be submitted, the oldest Italian ancestor must have still been alive on or after that date.
So, in the case of my friend, he’s in his 50’s (like I am), his parents are in their 80’s (say, born in 1940’s, like my parents). So, my grandparents were born around 1920, and then my great grandparents were born between 1890 - 1900. So, 4 generations, maybe 5 if kids were every 20 years.