Gets / Sets if a common BasicEffect and AlphaTestEffect should be used for all particle systems, rather than each particle system creating their own.
NOTE: Using a shared effect will decrease the time it takes to Initialize() each particle system.
NOTE: If using a shared Effect for all particle systems, if one particle system sets an Effect parameter, all other particle systems should also set that same parameter in their overridden SetEffectParameters() function so that each particle system guarantees that the Effect is using the parameters it expects it to be using. For example, if particle system 1 sets the Effect's Texture, that same Texture will be used for particle system 2 unless particle system 2 specifies the new Texture to use.
NOTE: The Graphics Device of the first particle system to be initialized will be used when creating the shared Effect. If you later require a different Graphics Device to be used, you must call the SetGraphicsDeviceForSharedEffectsForAllParticleSystems() function.