SEASON FOUR OF Pamela Adlon’s FX series Better Things, created, directed by, and starring Adlon as an actress and a single mom raising three eccentric, steel-willed girls, boasts four episodes that are stone-cold classics, endlessly rewatchable and rewarding. The rest of the season is pretty good too—so nervy yet exact that it makes almost every other American TV show, even excellent ones, seem formulaic and timid in comparison. The series is filled with believably awkward, occasionally volatile, but always humane moments among Adlon’s Sam Fox and her daughters (Mikey Madison, Hannah Alligood, and Olivia Edward) and her friends, colleagues, and exes (including her deadbeat ex-husband, Xander, played by Matthew Glave). It’s about the sisterhood of all women, particularly mothers and daughters of one kind or another; variants of the observation…