Doubt, Full screen Texture or Image Effects? Do oversdraw really matter?

Im working in a game and things like vignete or gradient color effects are done in the shader in one pass, but i have saw many projects than instead of using image effects they just put a vignete texture in a big quad in front the camera, or if they want the sun to shine more orange from the top right screen, again, one texture (big or small) that cover all the screen with some material (now you have 2 textures in full screen one in top another).

The result is good because it looks the same as photoshop, but why use camera effects if u can achieve the same using a faster and easy technique? transparency materials and overdraw are no problem anymore?

I remember a GDC video about a 2d game and they made all the sprite fit really well inside the mesh to reduce overdraw to minimum, is that old school stuff?

 

so i test it.

1 - Camera effect Unity
2 - Big plane in front the camera with a texture
3 - Big plane in front camera with shader
4 - Own camera Effect.

1. the wort, almot 3x time expensive than using a texture, for gpu and rendering,memory.

2. actually this is a lot faster,but you have 1 to 2mb more for the texture.

3. is the best, not using a texture but using a shader (uv distance *0.5), fast as texture but with no memory rending at all.

4. is a lot faster than the unity camera effect, but as is a camera effect i have some 20-40 mb + for rendering.

For mobile the number 3 is doing really well.

 

how to call multiple animation on single object ....but it divide in parts ....like i have a cube which we make with 6 plane then attach it.....after that when i click on one plane call one animation same as when i click second plane ..two animation call... like that i want to call 6 animation....