I do both. Some days ill build my lather in a bowl then brush it on and shave. Other times i build lather in a bowl and finish building the lather on my face to get a little scrub time on the skin. Other times i just go right to the face and use the bowl just to soak my brush while showering.

Its all personnal preferance. If you can build the same lather no matter how you go about it is the trick.