I keep my soap pucks in separate bowls - I have a ramikin and an Old Spice bowl. Then I use a separate bowl for fully building the lather. Actually, I have a few different bowls which I use for lather building. I haven't found just the right one yet. I think you'll find most folks do use a separate bowl for building lather. The lather bowl can have little ridges in the bottom, for example, to help incorporate air into the lather which isn't possible if you build your lather directly on the puck.
VdH Luxury, Speick, C.O. Bigelow, Real Shaving Cream, AOS, Cella.