I think this is a new feature, at least I have not noticed it before. Probably not new as of this day, but fairly new. It is now possible to level up a crown skill by testing out of its current level.
On the web version, when I click on a skill circle, there is a button with a key. Clicking it lets me test out of that level. It takes about as long as a random exercise and gives a truckload of XP, so it is like hitting jackpot. Well, if you manage to do it with less than 4 mistakes. They won’t make it easy for you, they say. But if you’re a bit down the skill tree, then the first bubbles are probably pretty easy, so why not max them out. Especially if that means you won’t get to see them more, or at least not for a long time.
This is a quick way to get a lot of XP (which admittedly means less than before, since levels aren’t really a thing now that we have crown levels). If you have a high daily goal, it is probably more important – I have only 20, which frankly is a bit on the low side for Japanese. It is just that after my daily quote, I already feel kind of wrung out mentally. But I think I have told you about this already, how I feel mentally exhausted even when I get everything right, something I never experienced with French or German. Anyway, as long as you have some easy skills that are not maxed, you can get a full day’s XP in the time it takes to do one dumbbell. Also you get a free lingot.
In the past, I could not be bothered to go through the loooong row of exercises to max crown levels in a skill I already found easy. But now I can max them out quickly, so this was definitely a nice discovery.