This model is almost entirely overhangs with small gaps between them, making support removal a pain. This way uses less filament and makes for better quality
This particular model would have lots of troublesome bridging if printed vertically, and would need supports along the entire length if printed horizontally.
Is this what we're referring to? To summarize (if I've understood this properly): Printing at 45 degrees ensures none of the print's three axes are aligned with the printer's least accurate axis of movement.