I have a 6th, 2nd, and 1st grader using this. I give 25 seconds, 50 questions right, and type it 2 time when they get a wrong answer.
When I first started this with my oldest who was super math phobic I gave her literally 60 seconds per question.
Another hint – less is more. Focus in on one set of facts and they’ll really master them. Then start the next set of facts, etc. Oncce you have a few mastered be sure you make a ‘facts review’ lesson they do every other day or less often to keep up on those facts (they’ll do fewer of each family that way, so be sure they’re mastered first).
We tend to do single fact family lessons daily and then twice a week do a review lesson with all past facts (still only 50 questions).