Serviceability

As’salamualaikum Sir, I wanted to know if the long term and short term deflection of Slab needs to be checked at serviceability condition or design condition. I mean, do we need to use the stiffness modifiers of Serviceability condition for checking the elastic and long term deflection of slab? Deformation always comes larger in design condition than the serviceability condition. That’s why I am a bit confused. I will be grateful if you clarify.