Everyone has their own technique for applying epoxy. I like to use only a squeegee for most jobs and don't use a roller at all. If you use a roller to apply the epoxy, then you are right, the main job of the squeege is to remove excess resin. Gently draw the squeegee across the wet-out laminate; stop the squeegee on the surface and then lift it. If there is an appreciable bead of epoxy left on the surface, it is too wet. Use the squeegee to lift epoxy off the surface and back into your cup. The squeegee also helps to compact the glass and bring up any epoxy that is pooling below it and remove trapped air. As you work the glass with the squeegee, the glass moves slightly. Be aware of this motion and use it to your advantage. If you are getting bubbles at the inside seams due to the glass bridging across, then use the squeegee to pull the glass from the edges towards the bubble. If you have a wrinkle, follow the fibers from the wrinkle out the edge of the part and pull the fibers there to straighted the glass.