PtolemysXX wrote: ↑Sun Jan 22, 2023 2:36 pm
There is no reward for finishing a course.
My feeling is that Duolingo does not really care
2-3 years ago the "friend updates" exactly showed events like user X completed their abc language tree.
User Y reached crown level 2-n in their abc language tree.
Something useful you can say....
When I finally decided to complete the very last three lessons in three bottom skills in my DE<-PT reverse tree before 04. January 2023 which I worked a longer time on with multiple shorter or longer breaks I got no congratulation messages from the friends updates.
Also the crown level up messages where disabled again by staff 1-2+ year(s) ago.
But those annoying "user Z got a 7-14 days streak" messages are still shown on the friends updates.
Or "user W did 10+ lessons a day" or "..jumped to the next League" not so useful messages are still flooding my stream.
PtolemysXX wrote: ↑Sun Jan 22, 2023 2:36 pm
On Android when I complete the last skill I can download a picture that confirms the accomplishment but it does not mention the level of completion
The Duome page does, at least for now.
PtolemysXX wrote: ↑Sun Jan 22, 2023 2:36 pm
yet there is a huge difference between level 1 and the legendary level.
Fewer than 0.1% of users completing a tree, so why bother…
I first completed the Portuguese tree with 69 skills and 406 lessons in the pre-crown period end of 2017.
That tree got updated in summer 2018 and has had 91 skills and 463 lessons until recently.
There are 75 units on the new path/snake.
Some trees like contributor German from English or French from German where a bit longer (>100-13x skills) but still manageable, so you had a good chance to complete them within 1.5-1.75 years, maybe a bit longer.
My personal impression of the super long CEFR Spanish and French staff-based trees, which got extended again and again, never was that a normal human on earth can actually complete them.
Users lost progress again and again for the non-compatible CEFR migrations in 2018-2019.
My English from Portuguese tree (CEFR, staff took over in 2018 and rolled it out to me in 2019; several incremental updates followed so it can definitely keep up with English from Spanish CEFR course) got bigger replacements and some parts where redone 2-3 times for new sounds or new challenges so I lost progress not only once. Well, it's just a reverse tree for me...
Some long-term and advanced learners may have also been working on higher crown levels, reflected by a very high 75-150k or higer course XP score.
But too many beginners followed the wrong/suboptimal learning concept (even for Latin languages) and overworked on all early skills without any spacing and never tried to push through the whole tree with 200+ skills at least on a L1-L3 crown pyramid system to get that golden owl.
With the new path and forced repeating levels integrated it might take even longer to complete a tree as you can't do only the first L1 crown level anymore, like you could do in 2016-2017.
Even the new crown concept gave you the freedom to do this in 2018-2021.
For example:
I already have one year of French learning under my belt (Busuu) and 6 years of Brazilian Portuguese.
It doesn't make that much sense then to follow a strict Duolingo path or to be forced to complete ALL skills on higher crown levels with the Pt->Fr or De->Fr courses or reverse trees.
Somehow it's good that English reverse trees and Spanish as well as French courses somehow got overblown courses which might NEVER end for a lot of beginner learners as they have to give up too early.
At least nobody can complain now that they completed a shorter course and don't know what to do afterwards 
But it surely is nothing for a shorter 1.0-1.5 years time range.
Not even 3.8 years to be realistic (only kinda realistic for the lower crowns).
https://ardslot.com/duolingodata.html
I knew for sure that I wouldn't be able to complete that long French tree to its very end.
So I held back to start one of these monsters and would focus first on the two other but shorter Duolingo course options (gives the big picture about Romance grammar, verb tenses and Subjunctive much sooner).
Didn't even start the old French contributor tree3 (A/B, 96 skills) which I caught in 2018 as several users got migrated too soon to the other CEFR tree design.
Nobody was pleased to lose their progress, so I didn't bother starting it. But could have as I was not migrated any earlier than 2019, 0.75-1.x years later.
The Duome course learners vs tree completion data is not very high, that's true.
But under these circ*mstances that's somehow understandable.
Also keep those earlier FR, ES and EN learners in mind who have actually completed their tree not only once but one of the last CEFR content updates or rearrangements still has taken again their golden owl away.
Duolingo shouldn't be a full-time job if you want to add 2-3 more resources.
Native | 
Upper-B2 (BritishCouncil) | 
L25 (Duo) / A2 (6+y, McGraw-Hill) - Learning (Busuu): 
(A1 McGraw-Hill) | 
(interm.)
