Just supports, I had to manually paint them in to prevent the slicer from putting them all the way up the side

Looks like the model is just resting on supports. Might have a roof or "support interface" (a layer between supports and model)

I think OP is putting it at an angle so there are no 90 degree overhangs and so the model doesn't need support added or removed.

Less overhangs?

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.

It really depends on what you're printing, how strong you need it to be, and/or what axis you don't mind looking uglier because of layer lines.

In this case OP might have been able to print it on a side with minimal supports, but the idea is that printing it at an angle turns things that would have been overhangs (which are hard for printers to do because of the melted plastic sagging) into upwards slopes. The alternative is adding support material that is intended to snap off (i.e. The block at the bottom of this picture), but those would be hard/impossible to remove in models like OP's that would have supports inside the holes.

That’s a great idea and would require similar amounts of support, however there’s still going to be 90 degree overhangs that wouldn’t come out quite as nice as the orientation I used

The model in question only has 1 flat side, its end (which is the top in the photo). Every other side requires supports if it’s on the build plate because of the recess in the cap, and the cap being wider than the rest of the model