I have been stuck on the 4th week for a few weeks now. I got through it the first time - on the first tier - but then my test put me on the second tier of week 4, rather than any of the week 5 tiers (i.e. minimum 31). And I've been stuck on that second tier for a couple of weeks now. Had a small set back yesterday when I couldn't finish the last set, like I had the week before, but I am getting better, which I guess is the idea and I'll keep doing the second tier of week 4 until I complete it perfectly and can then retest and then I'll go wherever the test puts me.