Noticed something interesting
I opened a second account to do the Gaelic tree a second time (without losing all the XP and crowns on this account), and my initial plan was to bring every skill up to the 4th crown so that I would have a nice set of the top-level exercises to do, potentially again and again if I just kept crashing out of the lesson before I got the XP.
I was slightly spooked that as I progressed down the tree the top crown level began to be filled in on the earlier crowns, to different extents but with a couple it went well over 60%. This wasn't leaving me much of the top-level lessons, which was kind of the point of the exercise. I started taking the later skills only to the 3rd crown to try to compensate for this.
I do remember this happening when I did the tree the first time as well, although as I gilded the skills relatively quickly it didn't make a huge difference.
Well, the other day the problem went away. All these gratuitous credits at the top-crown level that I really didn't want have vanished. I'm well on my way to having an entire tree at the 4th crown so that I can practice all the most advanced lessons again. And again.
But if only the "practice lessons" we get on the gilded skills were at that level, I wouldn't have to go to all this trouble.
Yes. I was just so pleased to get the full set of top-level lessons back. For a while it seemed that Duolingo did not want me to have the chance to do these again because after locking them away from me on the gilded tree they started filling the top level on my second tree in without me actually having done the lessons. At least that's gone.