Adverbs & Expressions of frequency

ADVERBS OF FREQUENCY:

Always (siempre), often (a menudo), sometimes (a veces), usually (usualmente), hardly ever (casi nunca), never (nunca), ...

Adverbs of frequency go BEFORE the main verb.
Adverbs of frequency go AFTER be.
He always travels by by bus./He's never on time.

EXPRESSIONS OF FREQUENCY:

Every day (todos los días), once a week (una vez a la semana), ...

Expressions of frequency go at the END of a SENTENCE.
I have classes twice a week.