Why do some languages have more lessons and how often do languages get updates?
I heard that some languages like German and Welsh have some of the longest trees while others like French have a little bit less (though still relatively a lot). So why do some languages have more lessons than others?
Also, how often does the French tree (or trees in general) get updates? Why aren't there more updates?
Apart from the original handful of courses developed by DuoLingo's staff, every course here is developed by volunteers who do not work for Duo. The amount of skills and lessons within them is decided by the teams that work on them. That's why some courses are longer than others, why some have real voices and some have text-to-speech, why some have missing audio, and why their quality is extremely varied.
I know that months, or even as much as a year ago it was suggested that they add an additional checkpoint. I don't use them myself, but I find they break up the tree into sections and makes it look nicer. Right now the tree has 41 skills between the last check point and the end of the tree. From the little I have seen of other trees that is a lot of space between checkpoints.
Of course, but from the perspective of a user the languages with more/better volunteers is quite arbitrary, it's mostly not dependent on what languages the tree involves so there's no way to tell how long a tree will be without just looking at how long it is (same applies for updates). That's what I meant in my post (of course it's not actually arbitrary like there's a RNG that decides the tree length or something).