You have to know that understanding and recall are not the same. They vary in amounts enormously, and the factor that defines their difference is your own time management. What you understand you do not necessarily recall, and as time progresses while you learn, you will recall less and less of what you are understanding.
What you are looking for is a learning situation in which both recall and understanding can work in maximum harmony. You can create this situation only by organising the time in which you are learning in such a way as to enable understanding to remain high without giving the memory a chance to sag too deeply in the middle. This is easily accomplished by learning to divide your learning periods into the most beneficial time units. These units, on the average, turn out to be between ten and sixty minutes, and your breaks should usually be no longer than two to ten minutes.
So, first this application will permit you to organise really precisely your learning time by giving you strict units of time.
Moreover, it will permit you to gain a certain self-discipline, on one hand by preventing you from using your phone and on the other hand by supplying you a strict temporal setting to learn.