It depends on what vfx you want to create and where they would be looked at from. Are these meshes flying in the air, laying flat on the ground, looked at from first-person/third-person view, top-down view?
These would determine where the seams would be placed so they are less visible to the player, thus creating a more immersive effect.
Regarding your top view and how thin your mesh is, I would say you could only have a flat plane with projected uvs 
I honestly might do that or make mesh thicker
you could also just use a single mesh shuriken and duplicate the amount to your liking on rotate around point and a spawn burst
Might give that a shot. Reason i didn’t is i read in another vfx post that Rotate Around Point is less performant.i know that doesnt really matter for demo reel, but i was still trying to learning some good habits.
I actually meant to use a flat plane for a single shuriken like @Jack_o suggested, it would be way cleaner to make a single mesh and duplicate the amount directly in Niagara, imo.
Even if it’s for a demo, you should consider doing something versatile by using a single mesh per shuriken instance as it’s less destructive
I decided I will use a plane with a texture instead of a mesh. Will post result.
I think it’s great that you consider performance from early on!
However, in your particular example, I would recommend going with one shuriken and doing the rest/maths in Niagara, like Jack_o suggested.
Reason being: In production, this would be so much more versatile. If design suddenly comes to you and requests a change in radius, or customizable radius, or a change in number of shurikens, you would need to reexport the mesh every time, which is not optimal. Also, having the shuriken as solo mesh means you can use it for different effects as well and you can do more crazy stuff, like animating each shuriken on their own.
If you’re not developing for mobile, this tiny performance difference might not matter anyway, but if you are, you can always do these kinds of optimisations later, once the design and look of the effect are completely locked down.
Just a few thoughts, I know it’s probably not relevant here, as it’s only for your reel.
Good luck 
curious to see where you end up with this!
I think I forgot to mention, but it is a single duplicate mesh for the current effect. The one with 8 meshes was just for prototyping. I will still change to a plane mesh tho with a 2d texture I’ll make in Affinity Photo 2. I think I will do rgb packing so I can have the blade, motion lines, and maybe a radial gradient in separate channels. Ill post what the system looks like currently with the mesh before I change it to a plane.
I’m guessing I would do this following part using Blueprints (to make each blade in the index of the Normalized Position a different color, but i also need them not to overlap, so “I need to make it so u pick the number of Blades, AND each blade lets u assign its own material, AND also retains a Normalized Index”
Over-Explanation:
- There should only be the chosen # of blades
- Assign Each a material
- Keep Normalized Position
Update-I cheated it manually for now or tried to at least by manually moving the Index Positions
