18 minutes of serious study/training a day for 90 days = 27 hours dedicated study.
18 minutes a day of serious study/training a day for a year = 109.5 hours
Colleges in the old days (before purple hair) would give you a Bachelor's degree for 26 semester hours , and a Master's degree for 45 hours, while it would take between 80 and 93 hours to get a PhD in Science.
So, study intensely on your own for 18 minutes a day for 90 days to become an expert.
Do it for 6 months to become a master.
The kicker is that if you do almost anything for 18 minutes a day for 21 days it becomes a habit....so success is guaranteed.