Do you mean graphically or getting all achievements etc? Most people on these forums will most likely try and max games out they own due to it being a PC enthusiast forum
The later part though, no idea. I only go for achievements if they actually sound fun or add to the gaming experience in some way.
Usually everything other than shadows (Which I keep on medium) and AA (Which is usually around 2/4x depending on how the game looks jaggies wise).