When we want to express something that is not always the case, there are several synonyms we can use. One common expression is "not necessarily," which implies that something is not always true, but it could be. Another option is "sometimes," which suggests that something occurs occasionally but not always. "Intermittently" or "sporadically" are other alternatives that imply irregular occurrence. "Occasionally" is another word that suggests something happens only once in a while. "Infrequently" is another synonym that conveys the idea of not happening often. Lastly, "rarely" or "seldom" indicate something happens very infrequently, if at all. Overall, these synonyms offer a range of options to express the idea of "not always".