I find that when using a smaller brush I often have to go back to the soap after the second or third pass. If the lather evaporates from the brush or if I add too much water to the brush, I'll go back to the soap to balance it out.
Despite the above poster's vociferous protests, I load my humble boar brush at the beginning of the shave, shave 3 passes, and wash away the remaining perfectly good lather from my brush. I do this every day. Must be magic.
...Reload causes a huge mess because the puck is dry, and you have to create the lather again. I usually create it in a separate bowl so I can go in there for extra if I need it.