Adverbs of frequency (often, sometimes, always, usually, ...)
are usually put between the subject and the verb, but they can also go in front position (except always, ever and never) or in end position.
Nick usually buys a pair of skis every year.
He often meets his best friend. We don't visit them very often.
Sometimes they go to the movies on Sundays.
!!!! I have NEVER seen an alien.