<p>This is really an individual choice. I personally think that 40 minutes is too long to study at one time. I would just study about 20 minutes at a time. If you want to do 40 minutes in a day, then try splitting it up into two 20 minute sessions. This leads to much greater retention. And it’s ok if on some days you only study a total of 20 minutes. If you’re studying correctly over a 3 month period, then this is quite effective.</p>