As indicated in the table design advice of the last recipe, instead of repeating identical values in adjacent cells, you could leave the other cells empty if the reader would be able to understand that the same values apply.
We can support the meaning by merging cells and centering the cell value over the whole new width.
Merging and centering can be done horizontally, vertically, or both combined. We will start with the horizontal method, spanning cells over multiple columns. You can see this often, with table headers that apply to several columns. So, in this recipe, we will conflate header texts.
As modeling clay, we will take the differences between various LaTeX compilers. While LaTeX remains the same, the underlying ...