The word 'frequent' is a correct and usable word in written English. You can use it when you want to say that something happens or is done often. For example, "The student visits the library on a frequent basis.".
Earthquakes are frequent.
The original buildings, constructed from dung and straw, tended to collapse whenever hit by one of the country's frequent earth tremors.
Flashman's increasingly frequent appearances at Westminster are now being remarked upon even by MPs in his own party".
These thefts, and the frequent contests which they produce, have for some time furnished a constant fund of amusement to the bystanders.
In fact my home is quite fragrant, and the smell that's likely to waft the way of our frequent visitors is not urine but the spaghetti bolognese boiling on the cooker to feed the three kids.
Particularly frequent or prolonged exposure to very loud sound can permanently damage the ear's sensory cells, causing irreversible hearing loss, and even deafness.
Armed incursions from Darfur are frequent across the porous border, endangering humanitarian convoys on the 11-hour drive from the nearest gravel road.
Being a terminologist, I care about word choice. Ludwig simply helps me pick the best words for any translation. Five stars!
Maria Pia Montoro
Terminologist and Q/A Analyst @ Translation Centre for the Bodies of the European Union