Random Seed

Many effects, like most of the the UV and Mesh effects, will use Time to animate. The Time value is the same for all instances, meaning that all instances of a material, will by default have the same animation timing and will look synchronized with each other. To give each Material instance a random time you'll need to add this component to the Gameobject that has the Renderer (like Mesh Renderer, Skinned Mesh Renderer, Sprite Renderer...) that you want to affect:

And as a reminder, to have materials visually update in the Scene view check the Always Refresh option in the top right corner of the Scene Window: