Quick check
Tap a Spanish word, then its English partner
los domingos means every Sunday
English marks the difference with words: "on Sunday" against "on Sundays". Spanish marks it with the article.
Los domingos duermo y veo Netflix. Every Sunday, as a habit.
El domingo estudio porque tengo examen. This coming Sunday, once.
The trap: the day itself never changes for lunes to viernes, because they already end in -s. Only sabado and domingo add one: los sabados, los domingos. And days are written in lower case.
The four slots, in this order
Your notes give a fixed order for a habit sentence, and following it keeps you out of trouble:
day of the week + time of the week + activity + frequency.
Mi momento preferido es salir una vez a la semana por la noche.
The trap: a clock time takes a las, but a part of the day takes por la. Both can appear in the same sentence: a las diez por la manana.
Frequency words worth memorising as a block
siempre · casi todos los dias · a menudo · normalmente · dos veces a la semana · una vez a la semana · a veces · nunca
Una vez is once, dos veces is twice: vez becomes veces in the plural.
The trap: the class quiz asks which expression is habitual and offers ahora mismo, una vez en la vida, todos los lunes and hace mucho tiempo. Only the third is a habit.