Shapes, their sizes, and the layout grid set the balance of a slide. But text as well and is often overlooked. Watch out for these:

• One word that drops to the second line
• A very long word that makes a sentence break halfway the page
• 3 boxes in a row, 2 with little text, one crammed with characters
• Long descriptors in column headings that break line after line after line

The solution in these cases is not reducing the font size, reducing the margins, it is redesigning your slide layout and content:

• Take out filler words
• Replace long words (management, manufacturing) with shorter ones
• Splitting a point in 2 points that are more balanced
• Making a sentence actually longer to restore balance
• Flipping the rows and columns of a table
• Using a different shape (circles and long text do not go together for example)

Art: Jean-Honoré Fragonard, The Swing, 1767