When does Excel decide to overflow text into adjacent cells, or cut them at the ...

In Excel 2010, or any other version probably, if I enter in a cell a long single-line text that is longer than the width of the cell, Excel sometimes render the text across the next adjacent cells; some other times, it gets cut off at the boundary with the adjacent cell to the right.

I would like to know how does Excel decide what to do, so I can better control my layouts. Note that I do not want to use merge cells, as it is inappropriate at times. Also, I already tried "Clear All" formatting on all affected cells but it still doesn't seem to reveal much.

Any ideas?

For text to overflow beyond the edge of a cell, the following conditions must be true:

• The cell does not have "Wrap Text" turned on
• The cell is not a merged cell
• The cell contains a value that exceeds the width of the cell
• The adjacent cell is empty* and not a merged cell

• The cell has any of the following horizontal alignments:

  • General
  • Left (Indent)
  • Center
  • Right (Indent)
  • Center across selection
    (Right overlaps the cell to the left; center overlaps on both sides.)

• The cell contents are not rotated (i.e. orientation is set to 0°) _{(Excel 2010 only?)}

• The cell contains a text value. Numerical and date values get converted to ####, or to scientific notation, instead of overlapping adjacent empty cells.
• The worksheet does not have "Show Formulas" turned on

I believe these are all the necessary conditions. If I have missed any, please feel free to edit this answer.

_{*In certain circumstances, an adjacent cell can appear to be empty, but not be, in which case the text will not overflow into that cell, because it is not truly empty. For example, if the adjacent cell contains a formula resolving to "", then it is not empty.}