As to the length of the study sessions, studying a little every day is usually more effective than enduring painfully long but infrequent study sessions.
فلا يمكنك ان تتقن السباحة بمجرد قراءة كتاب ،‏ فيلزم ان تخوض الماء وتمارس ما تعلّمته .‏