Use Excel all day, and F4 saves me more work than almost any other shortcut

Excel power users may rely on familiar shortcuts, but one key—F4—can save more time than most others. The article explains three main uses. First, F4 switches how cell references behave while editing formulas: pressing it cycles through relative and mixed absolute references, such as turning E2 into $E$2, E$2, or E2 depending on what you need to lock. Second, F4 repeats the most recent action, such as matching column width settings or reapplying formatting made in a dialog box like Format Cells. The piece also notes that using mixed references can help maintain consistent behavior in conditional formatting rules.