Yes, you can use Magoosh to study for the new GMAT Focus! Once you're signed into your premium plan, head to your Account Settings page and click the green Edit Account Information button. From there, you can switch to GMAT Focus:
Once you've switched to our GMAT Focus dashboard, you'll be able to select a GMAT Focus study schedule and have access to shorter GMAT Focus practice tests!
Please note: If you have already been studying with Magoosh, the new GMAT Focus dashboard will appear as if you've started over. However, answer data from the original GMAT dashboard will still remain saved, and you can review previous answers on your Review page.
Finally, I want to mention that our GMAT Focus product comes with 830 questions, not 1300, due to the removal of certain types of questions.