Summer has begun! It's time to pursue our goals! It took me around 12 hours separated over 3 days to complete the practice and pass Outlook 2019. Let me share my thought regarding MO-400.
I did LabSim and GMetrix practice provided by our professor. However, I found that the LabSim version was so outdated, with approximately 70% of the user interface changed. After completing LabSim, I proceeded to GMetrix and realized that I didn't even know how to answer the first few questions... If I were given one more chance to prepare for MO-400, I would only do the three GMetrix practice twice.
I think hitting MO-400 is a good start in summer. What you need is a good habit to keep learning without instruction and deadline. Then, We can easily get one more certificate for free which originally costs around $100.