Hello:-) It is very important to study regularly, perhaps a half hour a day. Even we have closed the textbook and begin to do anything else, our brain continues to work unconsciously. And so, sometimes, when we are walking, washing up or doing anything else, the solution of problem arises simultaneously. If we don’t maintain this work regularly, we begin to forget some knowledge much more quickly. When I have to leave my study for a long time, it is very annoying to repeat my knowledge again. And it is one of the most difficult and unpleasant things for me. Because it is much more interesting to go ahead and study something new, than repeat that you have already studied before. My language level is too low to give an advice, I just want to share my observations. Have a nice day!