I like to make use of time variable to animate the max value in “Smooth node”, is it meant to be used this way? Initially went with the keyframing approach but SHOP doesn't allow it. Is there a way to force it to do so?
You have to MMB on the “Max” input and select “Promote Parameter” and a Parameter VOP will be created automatically. Jump up a level to the SHOP and you'll find a “Max” parameter which you can keyframe or use $T/$F.