No. Silica has a moisture retention capacity and when the packet is full you have to bake it to allow the moisture to evaporate.
Leaving them in your case will only allow them to absorb as much moisture as they can and then after that point they will be useless. They are best used in a sealed package so that the moisture level INSIDE that package can be reduced to an acceptable level. The size of the packets determine which ones are needed for the area that they they will be absorbing moisture from.
Only if your case was hermetically sealed would this be of any benefit in reducing the moisture. But even then as soon as you open the case all the ambient moisture floods in.
Your cue has been made to be stable in most environments. Don't worry about it unless your case is made in such a way as to be retaining moisture and wrapping your cue in what amounts to a wet cloth. I live on an island and leave my cues in the car all the time and they stay nice and dry inside the cases.