Enable timesheet default view to be on the "grid" view, and allow a copy option to move projects and tasks from prior week or a template but with no hours. In this way, user can copy across last week, just fill in the numbers and submit.

Even better if the individual cells were able to contain more information than just the amount -- for instance that there are comments present, what is the role, and if it is submitted.

This could be with icons/indicators if the grid space were taking up more of the screen real estate.

Grid view would also be enhanced with totals at the bottom and information about utilization relative to target, historical trends, and other indicators/summarizations of the week.