|You can visit schedules while not logged in, but you do need to be logged in to do signups.
However if you are a normal user and login somewhere, your login on that PC will remain active for a year -- so long as you do not logout there or login on another computer. In other words, if you always use the same PC and do not logout, you generally do not have to login each time you want to do signups.
If you are an agent or administrator, your login will end if you exit your browser or shutdown your computer. There is a workaround though, you can do a Windows Hibernate instead of a Windows Shutdown at the end of the day.