There are several different medications that are now available as a long-acting injectable (LAI). The frequency of injections depends on which one is prescribed for you. Each LAI is given at differing frequencies of administration.
See this SMI CalAdviser tip, which shows all available LAIs in the U.S. including their frequencies
The National Alliance on Mental Illness (NAMI) also has some informative content on LAIs that might be useful to you. See this LAI information sheet.