Suggestion: "Unbounded" timed training
Instead of training only for 10 or so questions at a time, why isn't there a way to strengthen your language skills like the timed practice, that just keeps going touching every possible topic until you run out of time? This would be a much better way to strengthen your skills when you have a large backlog of "low-level" skills that need training than doing it a few questions at a time.
I think you are right. There should be a training that puts gold on all un-strengthened lessons.
Timed training is 20 questions max atm.
But it's a great suggestion to make since every end (i.e. finishing the 20 question) = an excuse to stop.
I've notice in the past when I used Memrise.for a bit that when reviewing a set amount of words, like 20 that you're quite unlikely to keep going to the next to reach i.e. 100+ in total while with unlimited reviewing you'll easily reach 100+ without even noticing it. With the overall amount of words you review in a single day often being a lot higher with the unlimited option.
But a system to detect when a user is getting bored (to end the session) might also be valuable to prevent people from overdoing it.
I like the idea, but I don't know if DL would consider adding such an option as it might seem a bit daunting for some users. Besides, it would only be useful for those users who have either ignored a lot of skills for too long, or for people going back to an abandoned tree.