We use the Time Journal to enter time that a resource forgot to include on their timesheet.
The timesheet has already been submitted, processed, and posted, and other invoices have been created and posted off of that timesheet. Thus, re-opening the timesheet is not an option.
Typically, on a timesheet, a resource will enter a billing note that prints on the invoice so the customer will have a description of the work that was done.
When we use the Time Journal, it is not possible to enter a billing note, and requires an extra step on the invoice side. It would be nice to enter the comment on the Time Journal so the comment stays with that entry on the project, and so it automatically flows on to the invoice.