Why are pipe clamps on a horizontal pipe assembled with 45° bolting holes direction?

Pipe clamps are assembled that way so that adjacent pipes can be placed closer together.

Three-Bolt Pipe Clamp and Riser Clamps Capable of Supporting both Horizontal and Vertical Piping
Three-Bolt Pipe Clamp and Riser Clamps Capable of Supporting both Horizontal and Vertical Piping
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