One approach is to use the 'Format Painter' tool in Excel. First, apply the desired conditional formatting to a single cell in the range. Then, select that cell and click on the 'Format Painter' button in the 'Home' tab. Finally, select the range of cells you want to apply the conditional formatting to, and the formatting will be copied across all the selected cells.

If you want to efficiently apply conditional formatting to a large range of cells programmatically, you can use VBA (Visual Basic for Applications) macros. Write a VBA macro that loops through each cell in the range and applies the desired conditional formatting based on your specified criteria. This approach is useful when you need to apply complex or dynamic conditional formatting conditions.

Another way to efficiently apply conditional formatting is by using the 'Format as Table' feature. First, select the range of cells you want to apply conditional formatting to. Then, in the 'Home' tab, click on 'Format as Table' and choose a table style. Finally, define the required conditional formatting rules for the cells in the table style options. This method not only applies conditional formatting but also allows for easy management and consistency.