Basically, the way that these pillows work is that when they are heated, they expand (the plastic will melt away) and fill the void. This maintains the fire rating and prevents fire from spreading and smoke spread is contained.
This is an old fashioned foam eductor and a bucket of foam. When is the last time you had one of these in your hands? How about the last time you actually flowed one? Well, unless you just completed a foam class or a Firefighter 1 & 2 class, it has probably been a while.
Know your assignments and do them. The best attack is a coordinated one when everyone is doing what needs to be done to accomplish the overall goal; safely get in and out after putting the fire out and removing all victims.
If the fire puddy or caulk is not completely around the cables or conduit, when the puddy/caulk is heated and expands, there will be a void on the side that the cable or conduit is touching the side of the pipe or sleeve