Weather plays a huge role, you either get lucky or you don't
I was in Fujinomiya in November 2022 and had excellent views, but when I was at Lake Ashi in November 2024 I did not see anything at all, Mt. Fuji was completely covered by clouds.
Same with taking the Tokaido Shinkansen, sometimes you see it, sometimes you don't.
They say that visibly is better during the colder part of the year due to lower humidity in the air.