Job Sheet shortcuts
Option-click any column of the Job Sheet list to change an entry.
 
Use the right and left arrow keys on your keyboard to go to the next and preceding Job Sheets respectively.
 
Type ⌘-Up Arrow key and Down Arrow to go to the first and last projects/matters in the Job Sheets sections, respectively.

Hit the Tab key to toggle focus into and out of the Job Sheet list.

With focus in the Job Sheet list, type Down Arrow and Up Arrow to go down through, and back up through entries, respectively.