I guess it mostly depends on what shows the TV-stations picked up, before these "cartoons" became known as "anime" - and before Streaming was a thing. In the early days, some shows even got extra episodes never shown on japanese TV (some released on VHS/DVD in Japan). But to become a successfull evergreen, one also needs a great dub and keep these voice actors...Huh. Interesting there, how different countries do localise different stuff. I know they do that with manga too considering there are french and german translated copies of manga of series I would like to get.
And that can be a problem, if one or more popular voice actors retire, die or just don't want to dub long running TV-series.
Due to the costs involved in dubbing anime, and people accepting prices like 7-10€ per episodes only for shorter series, long series still can't get european dubs without getting co-licensed by a TV-station. Sadly no TV-station was interested in Shojo-series (except Sailor Moon)