The phrase "are frequently assigned" is correct and usable in written English.
It can be used when discussing tasks, responsibilities, or roles that are regularly given to individuals or groups.
Example: "In our department, complex projects are frequently assigned to the most experienced team members."
Alternatives: "are often given" or "are regularly allocated".
Young people are frequently assigned several different diagnoses at the same institution, resulting in confused and ineffective treatment.
While administrators would never have a lifeguard at Jones Beach in February or a parking enforcement agent in a shopping mall at midnight, police officers are frequently assigned to isolated posts at inappropriate times.
According an American Civil Liberties Union fact sheet, transgender-related healthcare is frequently denied to transgender inmates in state prisons, and prisoners are frequently assigned to the facilities that correspond with their genitalia.
In social environments, rewards are frequently assigned on the basis of a winner-takes-all rule: this is true for example in sexual competition.
Annotations are frequently assigned a score, using a variety of methods.
As an example, relations whose importance varies are frequently assigned to biological data to capture the relevance of co-occurrences identified by text mining, sequence or structural similarities between proteins or co-expression of genes [ 23, 60].
The assignment of the absorption bands at about 1100 cm−1 was frequently assigned to alcoholic and polysaccharide C O stretching or to vibrations of a SiO2-related impurity in humic substances [31].
When the mass became a vehicle for choral performance in the 15th century, the Christe Eleison, certain parts of the Gloria and the Credo, the Benedictus, and the Agnus Dei were frequently assigned to a group of soloists within the choir.
She collided with the armored frigate in July 1869, and was frequently assigned to the Gunnery Training Detachment after 1870.
