Employers usually pay their employees bi-weekly or monthly. Their schedule is not random, however, nor is it just a matter of convention. Employee paychecks must be delivered according to each state’s per-determined timeline.
Employers cannot lawfully decide to pay employees whenever they want. They cannot make up a rule which issues checks every two months, for example. Some states don’t even allow for once per month pay checks. It is a good idea to know your state’s payday requirements so that you don’t ruffle any feathers and end up in court.
Follow this link on the Department of Labor website for a table of state payday requirements. Every state has slightly different requirements.