When a task is completed just for the sake of fulfilling a requirement or obligation, it is commonly referred to as "done as a formality". Other synonyms for this phrase include "perfunctory", "ritualistic", "pro forma", and "token". All of these phrases convey the idea that the task was completed simply to meet a requirement or follow a protocol, without a genuine interest or commitment to the outcome. Using these synonyms instead of repeating "done as a formality" over and over can help add variety to your writing and make it more engaging to the reader.