HelpDesk 3 will need to run 2 cron jobs to have all features working correctly.
All cron job files are in the folder cron and should be kept there otherwise you will need to modify the path inside the files.
Features like automatic reminders and automatic closing tickets you will need to run following cron job:
You should run this at least once day but not more than once an hour.
In case you have Email to Ticket set (also called PHP IMAP), you will need to run another cron job:
You should run this at least once an hour or every 15 minutes. Running it more frequently will maybe result in having your email account not responding due the limitation set on the server.