If you fail the quiz, don’t retry that one.

I can usually crank out a segment in a day if I feel like it’s slow. Since I also use other resources, I’ll skip ahead periodically.

If Duolingo is your only resource, you’ll have issues. You should be exploring other resources as well and using Duolingo as a way to get in some practice on the go. Most of my Duolingo use is on the toilet or while cooking, and I set aside time for more serious study.