70:5 If one person is still saying Maariv in shul at night, those who have finished should wait until he has finished so as not to disturb his concentration. If he began Shemoneh Esrei so late that he couldn’t have finished davening along with the congregation, they are not obligated to wait for him; his actions make it clear that he knew this would be the case and was unconcerned. (It’s still meritorious to wait for him – Mishnah Brurah 90:48.)
71:1 A person should establish a set time for Torah study after Maariv, as per Joshua 1:8, “You shall mediate on them day and night.” There is reason to be concerned that if one eats first, he may fall asleep, so one’s time for Torah study should be before eating. If a person is feeling hungry and weak, he should have a quick snack to energize himself and help his concentration. He should then learn a little Torah, after which he may eat his evening meal and then return to study more Torah according to his level of ability. The Talmud in Eiruvin (65a) says that night was created specifically for Torah study. This is especially true of long winter nights but one must be sure to learn at least a little Torah on short summer nights because of “mediate on them day and night.” From the fifteenth of Av on, as the length of night increases, one should gradually increase the amount of his nighttime Torah study. Resh Lakish said (Chagigah 12b) that one who studies Torah at night will enjoy G-d’s grace by day, as per Psalms 42:9, “By day, G-d will direct His grace, and at night, His song is with me.” Why does G-d direct His grace by day? Because, His “song” (i.e., the Torah) is with one at night. Others quote Resh Lakish as saying that whoever studies Torah in this world, which is likened to the night, will enjoy G-d’s grace in the Next World, which is compared to the day. If one did not complete his daily Torah study by day, he must complete it at night.