Please bring back Strengthen Skills on Android.
This probably won't make a difference, but hopefully Luis sees this.
The old strengthen skills was better than the new timed version, that's for sure.
But I'd like to see them both in place; perhaps with the mechanics of the timed one tweaked - either so that it would match the website version by increasing the time when you get it right or by giving a larger starting time. Some exercises are child's play to answer quickly, but typing a sentence in the subjunctive past on a phone keyboard when the clock is ticking 3, 2, 1 is not much fun and not great for learning.
Edit: also, the green box saying you're right gets in the way if you are too quick as you trap it above the next button. Then you lose time flicking it out of the way.
Also Duolingo V 3.50.2 (on Android V 7.1.1)
Maybe it is a Duolingo A/B test.
I tested four accounts on the same Android phone. Two of them have the "one-minute" against-the-clock-speed-test", but the other two don't have it.
If so I want out of the test. It's effing awful! I too have version 3.50.2. Don't know the version I had before but last Friday it was the regular workout and then Sunday I get this terrible timed test. I hope based on all the newly updated bad reviews in the Play Store they're roll this back.