Once you made entries, they will be saved & persisted even without you clicking an explicit Save button.
This is especially very useful when you are multi tasking & forgot to save or the computer crashes. That way you don't worry about going back & reentering them. Review collected by and hosted on G2.com.
It doesn't tell you whether a time sheet has been submitted or not. Also, the undo functionality after submission of the time sheet doesn't work on a consistent basis as per my experience. Review collected by and hosted on G2.com.