For some jobs, you won't need a cover letter to apply and some recruiters don't accept cover letters as a part of the application process. If the job requirements don't ask for a cover letter but if you can make one so try to apply with a cover letter it will make a good impression. if you don't have the time to compose a well-written one then hire cover letter writers in  Adelaide to make your cover letter look professional which will impress the recruiters. It depends on the company and the position you are applying but if it is optional and you think you can apply with a better one so it's better to skip it.