That is likely part of it and also explains why languages like Japanese are more tightly grouped, as there is less spread in word length for Japanese versus English or Italian.
I would guess, if it’s solid empirical work behind this, that there’s just greater differences internally between German and Italian speakers than for many other languages. Having lived in both Germany and Italy, I do not struggle to believe this is the case.
What produces the stretched graphs like Italian and German? What do these humps mean?
Variability in the length of words, loads of very short and very long words? Just a guess
That is likely part of it and also explains why languages like Japanese are more tightly grouped, as there is less spread in word length for Japanese versus English or Italian.
Maybe they didn’t account for various factors like age or mood.
Moreover, Munic has 130 words per minute and dortmund has 180 words. There’s a ddifference in the dialect
I would guess, if it’s solid empirical work behind this, that there’s just greater differences internally between German and Italian speakers than for many other languages. Having lived in both Germany and Italy, I do not struggle to believe this is the case.