For me the single most unpleasant job in modeling with plastic card is cutting out windows and doors. However, when you are using a sub wall to which you will be adding an embossed layer you can speed things up by scribing the outlines of the openings, with scribes in one direction extending the full width or height of the wall. Then you bend and snap all the pieces apart, discard the pieces where openings are, and gluing things back together. Then you add the embossed brick layer and cut out windows etc.
Perhaps you know this already.